Insomnia; and Other Disorders of Sleep

Worn out, friend, is every theory,

But green the golden tree of life.

-Goethe.

Natural sleep is that condition of physiological repose in which the molecular movements of the brain are no longer fully and clearly projected upon the field of consciousness. This condition is universally observed in all healthy animals; and its recurrence is intimately associated with the diurnal revolution of the earth, and the succession of day and night. The disappearance of daylight is, for the majority of living creatures, the signal for cessation of active life. Though its onset may be for a time delayed by an effort of the will, the need of rest at length overcomes all opposition, and the most untoward circumstances cannot then prevent the access of unconsciousness. The story of the sailor-boy, sleeping on "the high and giddy mast," is familiar to every one. An officer in the United States Navy has assured me of more than one instance in which men had fallen asleep under his own eyes, oppressed by exhaustion, during the roar of a long continued bombardment. Thus produced, the relation of cause and effect between weariness and sleep becomes very apparent. The refreshing influence of such repose points clearly to the restorative character of the physiological processes which persist during the suspension of consciousness. It also renders evident the final cause of that periodical interruption of activity which the brain experiences in common with every other living structure.

Sleep is usually preceded for some time by a feeling of sleepiness. This sensation, like the analogous sensations of hunger and thirst, represents in some measure the progressive diminution of energy throughout the entire body; but it is chiefly expressive of the failure of cerebral energy. It produces a sense of general heaviness and intellectual dullness; the special senses become less alert, the eyelids droop, numerous groups of muscles experience the spasmodic contraction of yawning, the head drops forward and is recovered with a jerk, the limbs relax, and the whole body tends to assume a position convenient for repose. Every school-boy who has been compelled to pass an evening hour at a dull lecture, under the eye of a martinet monitor, will testify to the suffering which attends any unusual prolongation of this period. But, if the natural course of events be not obstructed, the stage of mere sleepiness is soon passed, and the introductory stage of sleep is entered. This is a state in which the individual is neither awake nor fully asleep. It is known as the hypnagogic state. During this period the phenomena of simple sleepiness become exaggerated to such a degree that the attitude of repose is assumed without effort if the body be permitted to follow the natural inclination of its different members. The eyes close, the other senses become inactive, though the sense of hearing is the most persistent. Released in considerable measure from the control of the brain, the reflex energy of the spinal cord is at first somewhat exalted. Witness the fibrillary twitching of the muscles, and the convulsive state, which may often be observed during the stage of somnolence after severe fatigue. The uneasy sleeper may even be roused to complete wakefulness by such involuntary movements. But, as sleep becomes more profound, the reflex functions of the cord are also weakened.[1] As the sensory organs retire from action, the intellectual faculties lose their equilibrium. First, the power of volition ceases. Then the logical association of ideas comes to an end. The reasoning faculty disappears, and judgment is suspended. We become, therefore, no longer capable of surprise or astonishment at the vagaries of memory and of imagination, the only faculties that remain in action. To their more or less unfettered activity we owe the presentation in consciousness of those disorderly pictures which, occurring in this stage of imperfect sleep, have been termed hypnagogic hallucinations.[2] During the early moments of this period an observant person may often retain a power of reasoning sufficient to remark the fact of dreaming, and this effort of attention may produce a partial awakening; but, usually, the subsidence of cerebral function is progressive and rapid. The fire of imagination fades, the field of consciousness becomes less and less vividly illuminated, the entire nervous apparatus yields to the advancing tide, and, finally, the dominion of sleep is fully confirmed. The sleeper knows nothing of the external world, and has lost all consciousness of his own existence. But the duration of profound repose is brief. From the end of the first hour the depth of sleep, at first, rapidly, then, more gradually, subsides. Dreams disturb its tranquility, mental activity increases, the power of volition revives, and, at the end of six or eight hours, the individual is once more awake. The subjoined diagram, borrowed from the Dictionaire Encyclopédique des Sciences Médicales, will facilitate the apprehension of these successive phases in the course of sleep:

It was formerly believed that during the time of sleep all the processes of assimilation and nutrition throughout the body are increased,-in short, that it is the season of repair for the waste of tissue incurred during the hours of wakeful activity. While it is true that in sleep the expenditure of force is greatly reduced, the more exact researches of modern physiologists indicate a universal reduction in the rate of all the vital processes. The final result, however, is a general renewal of energy, because the aggregate income of the tissues is greater than their outgo during the suspension of conscious activity. The following observations make very apparent the fact of a reduction of physiological activity:

Respiration.-The process of breathing is conducted with greater deliberation during the period of sleep. This reduction is one of the most notable of the circumstances that first attract the attention of the spectator who observes a sleeping person. The average number of respirations per minute, in an adult of twenty-five to thirty years of age, is sixteen. Quetelet remarked[3] that during sleep this number was diminished by about one-fourth. The same fact has been recorded by other observers.[4] Mosso has also noted the fact[5] that there is a change in the type of respiration, the movements during sleep become less diaphragmatic and more largely costal. He furthermore observed that during the waking period the act of inspiration consumed 8-12 of the complete respiratory phase, but during sleep it was prolonged till it occupied 10-12 of the same cycle. The interval between the end of expiration and the commencement of inspiration was also obliterated by sleep. Notwithstanding this relative increase of inspiratory motion, the quantity of air that passes through the lungs is considerably reduced by reason of the diminished action of the diaphragm. A corresponding reduction of the gaseous exchanges between the blood and the external air has been determined by the experiments of Pettenkofer and Voit, Boussingault, Lewin, and other equally competent observers.[6]

Circulation.-During sleep the heart beats less frequently than during the waking hours. Though a portion of this delay must be attributed to the recumbent position, sleep does still further retard the movement of the heart. My own observations upon children in bed exhibit a difference of twelve to sixteen beats between the pulsations when awake and asleep. According to Trousseau[7] the average number of pulsations observed in a group of thirty children, varying in age from fifteen days to six months, was 140 when awake and 121 when asleep. In another group of twenty-nine children, between the ages of six months and twenty-one months, the average was 128 when awake and 112 when asleep. The observations of Hohl and Allix[8] indicate that among very young children the difference between the pulse of sleep and the pulse of wakefulness may equal forty beats. According to Guy (loc. cit.) the pulse is more variable in the morning than during the afternoon or evening.

Temperature.-Aside from the almost hourly fluctuations of the bodily temperature, a noticeable sinking of the temperature-curve is observed during the hours of sleep. This alone is sufficient to indicate a diminished rate of combustion in the tissues. Boussingault found[9] that a dove which consumed 255 millegrammes of carbon every hour while awake, oxidized only 162 millegrammes when asleep. Scharling also observed that the quantities of carbon successively oxidized by the same man when asleep and awake bore to each other the ratio of 1:1.237. The observations of Demme[10] indicate that increase of bodily temperature during the hours of sleep must be considered as the result of pathological processes in the tissues. The observations of Allix (loc. cit.), made upon sixteen children during the first twelve days after birth, showed an average fall of 0°.38 C. during the hours of sleep. Eight children, between five and sixteen months old, exhibited a similar depression of 0°.56 C.; while ten children, ranging in age from twenty months to four years of age, averaged 0°.34 C. less when asleep than when awake.

The well-known experiments of Chossat, who found that the temperature of pigeons was from 0°.70 C. to 0°.90 C. higher at noon than at midnight, may not be considered satisfactory evidence of the depressing influence of sleep, because it is true that the diurnal variations of temperature which are conditioned by the vital activities of every animal might be sufficient to account for these differences. The experiments of Horvath[11] are more convincing. This observer found that the marmots upon which he experimented were accustomed to sleep during the winter for about four days continuously, and would then remain awake for an equal length of time. "During the sleeping period they can be cooled down to such a degree that a thermometer introduced into the rectum to the depth of an inch and a half indicated only 3°F. above the freezing point. The temperature rose rapidly after the animal awoke, so that in the course of an hour it was 3°F. higher; at the close of the second hour 9°F. higher, and at the end of the next half hour about 27°F. * * Neither respiration nor the muscular movements were correspondingly augmented." This observation clearly shows the powerful influence of cerebral activity upon the liberation of heat within the body.

Secretion.-The functions of the numerous glands throughout the body are diminished during sleep. The tears dry up, and the cornea receives less moisture. Hence the stickiness of the margins of the eyelids during the sleep of a patient suffering with conjunctivitis. He can open his eyes, on awaking, only after sufficient time has elapsed to revive the lachrymal flow. Exner[12] remarks the diminution of pathological secretion in nasal catarrh during the hours of sleep. The mouth in like manner ceases to receive its full quota of saliva, and its cavity quickly dries if the lips remain open. The secretions of the gastro-intestinal glands vary with the contents of the alimentary canal; but in general they are considerably diminished, and digestion is correspondingly retarded during the hours of sleep. The quantity of urine is lessened during sleep.[13] The elimination of urea and of other excrementitious matters is less during the night than by day.[14] Unless increased by disease, or by accidental circumstances connected with atmospheric temperature and unnecessary clothing, the perspiration is also diminished.

Nutrition.-All the molecular processes of nutrition are reduced by sleep. The lowering of the bodily temperature has been already indicated. The observations of Helmholtz[15] indicate that the actual liberation of heat in the tissues is but little more than one-third of the amount set free in an equal period of time during the waking hours. The numerous experiments[16] of Boussingault, Henneberg, Scharling, E. Smith, Liebermeister, Pettenkofer, Voit, and Lewin, clearly indicate the fact that during sleep less oxygen is absorbed, and less carbonic acid gas is discharged, by the tissues. Voit found that while, during the daytime, 435 grammes of oxygen were taken in by a working man, only 326 grammes were needed by the same individual during the nocturnal half of the day. Artificial sleep occasioned by chloral hydrate produced a similar reduction in the consumption of oxygen and in the formation of carbonic acid gas. Under the influence of morphine the reduction of CO2. reached 27 per cent., and the diminution of oxygen amounted to 34 per cent. of the quantities furnished during wakeful activity. The comparatively small reduction (only 6 per cent.) in the decomposition of the nitrogenous elements of the body during the same period, exhibits the close relation between the metamorphosis of the non-nitrogenous elements of the tissues and the amount of bodily activity.

The experiments of Pettenkofer and Voit, to which allusion has just been made, serve also to illustrate the fact that all tissue changes are increased by every excitement of the sensory organs of the body, but are diminished by the subsidence of peripheral irritations. Hence the importance of quiet and darkness when we seek to induce that state of the body in which molecular processes should reach their minimum. Since every act of perception is attended by an outburst of refuse matter from the nervous tissue, the quantity of such excrementitious discharge in any given period of time becomes in some sort a measure of the vital activity of the organism. Conclusive proof of the diminution of vital function during sleep is thus obtained.

It must not, however, be inferred that the general reduction of tissue-change, which has thus been established, during the hours of sleep, is evidence of a universal and uniform reduction of function throughout the body. Sleep seldom falls at once with equal force upon every organ; its invasion is progressive. Consequently, certain structures may be fast asleep, while others are partly awake,-while still other portions of the organism may be in a condition of activity greatly in excess of their ordinary wakeful function. Upon this fact depend the phenomena of dreams and the various forms of somnambulism. The special senses are usually overcome by sleep before the muscular apparatus yields, and the cerebro-spinal nervous centres are the last of all to succumb. The eyes, for example, cease to see clearly before the eyelids droop, or the muscles of the neck give way in the act of nodding. The senses of touch and of taste fail next in order, as in the case of the infant gourmand, who may be seen falling asleep at supper,-his mouth yet filled with untasted sweets from the table before him. The sense of smell is more persistent, and its exercise is sometimes an obstacle to the invasion of sleep. Witness the effect of powerful odors upon certain persons. The perfume of flowering plants in the sleeping chamber is sometimes decidedly annoying on this account. A lady of my acquaintance was once awakened out of a sound sleep by the smell of tobacco smoke from the pipe of a thoughtless burglar who had quietly entered a distant apartment of the house. A sudden change of wind, deluging a city with the vapors of a glue-factory or rendering establishment, may in like manner disturb the slumbers of thousands of people.

The sense of hearing seems to be the most persistent of all the special senses. It is not a very uncommon thing for persons to be awakened by the sound of their own snoring; or, if not actually aroused by the noise, to remain in a condition of repose which seems to be sustained and cheered by the regular rhythm of its own music. As a general rule, however, it is noteworthy that, when not wholly dormant, each sense finds its sphere of activity greatly narrowed by the fact of sleep. Consequently the range of perception, if not wholly obliterated, is greatly limited during the time of sleep.

While it is true that sleep arrests the voluntary activities of the muscles, it is also a fact that all the muscles do not yield at once or in equal degree. The extensors of the neck, and the supporters of the spinal column, are the first to fail. The patient begins to nod, and is inclined to fall forward, before consciousness ceases. The muscles of respiration and of circulation continue to contract, though at a diminished rate. The vermicular movements of the intestinal coats persist, and in certain conditions of ill-health their exaggerated contractions may become a cause of imperfect repose. Reflex movements may always be excited during natural sleep. Tickling the sole of the foot will cause retraction of the limb; and before the complete establishment of sleep, a certain exaltation of the spinal reflexes may be observed. Young children may frequently be seen in the act of suction with their lips, as if at the breast; and the smile of the sleeping infant is a matter of daily remark in every nursery. The influence of dreams as an excitant of muscular movement will be hereafter discussed.

The variation of intellectual function which appears in sleep serves to measure its profundity and to indicate the extent of its invasion. The act of perception being dependent upon sensation, it is to be observed that the range of perception diminishes so soon as the organs of sense begin to yield. Its intensity may not immediately fail, but the breadth of its scope is narrowed. Sometimes, however, the act of conscious perception is arrested before the organs of sense are sealed. The sleepy reader may continue to eye the page before him, perhaps even to read aloud for a considerable time after he has ceased to derive any meaning from the words of the book. In such cases the organs of perception and conception and association of ideas slumber before the bonds of connection between the will and the muscular organs have been completely relaxed. Such an example affords a valuable illustration of the division of the brain into separate mechanisms which, though most intimately related, are nevertheless partially independent of each other. Sleep may operate like an invasive disease, falling with unequal incidence upon the different structures that make up the mass of the brain, paralyzing one portion, while simply benumbing another, and even arousing to excessive activity a third. Consequently the intellectual functions may be very unequally disturbed, and the order of their subsidence may be considerably varied; but, as a general rule, the physiological relations of the faculties are respected, so that as sensation diminishes, perception fails, the conception of ideas is correspondingly hindered, and the association of such ideas as are still projected upon the field of consciousness becomes more imperfect. The loss of the power of association implies the destruction of memory and the impossibility of exercising the reasoning faculty or of forming those judgments upon which every act of volition is based. When the brain has at length been so far overwhelmed that physical impressions can no longer reach the field of consciousness, all manifestation of intellectual life is at an end, and the sleeper sleeps a dreamless sleep that leaves no trace behind.

It is assumed in the last sentence that the brain may become so far transformed by sleep that it ceases for the time to be capable of function as the instrument of thought. This conclusion has been questioned by the very highest authorities. Sir William Hamilton, Exner, and many others have instituted numerous experiments to test the possibility of a dreamless sleep. Causing themselves to be suddenly aroused at all hours of the night, they invariably found themselves at the instant of awaking occupied with the course of a dream. Hence it has been inferred that the mind is always alert, even when the body is most thoroughly asleep. In explanation of the fact that consciousness contains after deep sleep no trace of such mental activity, it is claimed that the act of dreaming of which we are aware at the moment of waking is proof of intellectual function during the moments which preceded that incident, and that we are merely forgetful of all similar processes that occurred during undisturbed sleep. The unconsciousness of sleep, according to this theory, is not real-it is only apparent through failure of the memory. If this be true, memory is the only intellectual faculty of whose inaction we can be sure. The period of deep sleep might then be, for all we know to the contrary, a period of the most intense and exalted mental activity. But, if so, it is quite worthless as a constituent of our conscious existence. It may also be objected with equal reason that the dreams which unquestionably occupy the field of consciousness at the instant of waking are probably excited by the impressions which terminate sleep. The process of waking, though often very greatly hurried, is by no means absolutely instantaneous. As we shall learn, the time requisite for the evolution of a dream may be indefinitely brief. Consequently, it seems better in all such instances to assign the period of dreaming to the time of diminishing slumber that corresponds to the disturbance by which sleep was terminated.

The only reason for any hesitation in the acceptance of such a proposition consists in the reluctance of many philosophers to admit the possibility of any interruption in the active life of a spiritual being, such as man is conceived to be. But it is difficult to comprehend any valid reason for the denial of such interruption. Every form of force, of which we have any knowledge, is subject to fluctuations in the course of its phenomenal manifestation. When a physical force ceases to exhibit itself in an active state, and passes into a potential modification, we are not compelled to regard it as extinguished. It is merely latent or inhibited, but always ready to take its place again among the kinetic forces of nature. In like manner there seems to be no good reason why that spiritual force or congeries of forces which constitutes the mind of man may not experience analogous transformations in successive periods of action and of repose. Such periods of rest occur in sleep, in coma, in disease and disorganization of the brain. The mind sleeps, it does not cease to exist-probably not even when death dissolves its material substratum.

That the depth of sleep is exceedingly variable is evident in the experience of every one. A German physiologist[17] has made a rough estimate of the soundness of sleep by comparing the loudness of the noises necessary to wake the subject of experiment at regular intervals during the course of the night. He arranged a gong with a pendulum attachment, and noted the length of the stroke which produced a sound sufficiently loud to awaken the patient. In this way the different degrees of intensity of the awakening noise could be calculated, and the corresponding depth of sleep could be estimated. It was thus concluded that the depth of sleep increases rapidly during the first hour, at the end of which time it has reached its maximum. During the next half hour it diminishes as rapidly as it had increased in the first half hour. During the next hour it still further diminishes, almost as much as it increased during the second half hour. The remaining ten half hours of the experiment were occupied by a comparatively light and gradually diminishing slumber, until the vanishing point of sleep was reached at the expiration of eight hours from its commencement. This observation corresponds with the general opinion that sleep is deepest in the early part of the night. For the same reason dreams and wakefulness are most frequent during the early watches of the morning.

When considering the causes of sleep it is needful to exclude from view those artificial varieties of sleep that are produced by the various narcotic drugs, as well as the counterfeits of sleep which result from diseased conditions of the body. It is comparatively easy to frame hypotheses in explanation of such interruptions of our conscious life; but, when we attempt to formulate a theory which shall satisfactorily account for the occurrence of natural sleep in healthy animals, the task becomes exceedingly difficult.

First among the causes of sleep may be reckoned the alternation of day and night. With the disappearance of sunlight all nature sinks into a condition of repose.

"The night brings sleep

To the greenwoods deep,

To the bird of the woods its nest;

To care soft hours,

To life new powers,

To the sick and the weary-rest!"

In this tendency to nightly inaction man shares with all other living creatures. His body thus testifies to the intimacy of its relations with all portions of the solar system. Originated in the tropical regions of the earth, where day and night are nearly equal, we find in all parts of the world the same hereditary need of a period of rest, nearly coincident with the duration of the shorter nights of the tropical year. Had the birth-place of primeval man been situated within the Arctic circle, it is probable that his hours of sleep might have differed considerably from the number now needed by the average individual. So powerful are the necessities thus dependent upon the harmony between our organization and the movements of the earth, that if the habit be formed of sleeping at other hours than those which are usually devoted to that purpose, the full complement of sleep is still needful to satisfy the demand for rest.

Prominent among the causes which predispose to sleep at night is the cessation of a majority of the sensations that are continually pouring in upon the brain during the period of daylight. Hence the necessity for seclusion in darkened rooms, from which the noises of the daytime are shut out, if one would sleep during the long days of the arctic summer, or if one would enjoy a midday nap at any season of the year. The close dependence of wakefulness upon the constant activity of the organs of sensation, is well illustrated by a case related in Hermann's Handbuch der Physiologie, Vol. II, Part 2, p. 295. A young man had been reduced by disease to such a condition of general an?sthesia that the right eye and the left ear were the only remaining paths of sensation between his brain and the external world. Whenever the sound eye and ear were bandaged so as to cut off all communication with the brain, the patient invariably fell asleep in the course of two or three minutes after the interruption of sensation. In like manner, some people, even in perfect health, are able to sleep at any time by simply lying down and closing the eyes. Such persons, however, are not often very highly gifted in the intellectual sphere. They generally belong to a class of men whose lives are laborious and liable to great irregularity and fatigue. Such people labor in the open air, where every organ of sense is in a state of continual excitement. As soon, therefore, as they can find a quiet corner from which the commotion of the elements is excluded, it is only necessary to close the eyes-the principal avenue of communication with the outside world-and sleep begins at once. This is especially true if severe bodily exertion has preceded the opportunity for repose.

Fatigue of any sort is one of the most energetic causes of sleep. The impossibility of long sustained exertion is a fact almost too familiar to attract attention. Every muscle must be suffered to rest for a time after contraction before it can be again contracted. Even the heart and the muscles of respiration must be allowed to enjoy regular periods of repose many times each minute. These are examples of local rest, not involving the entire body. But if the whole body participate in any violent action, every part will manifest a consequent disposition to rest. Witness the effects of the venereal act. Every muscle is relaxed; the brain, which has officiated as the supreme source of energy, experiences exhaustion, and sleep frequently terminates the voluptuous paroxysm. In like manner, sensations of severe pain, if sufficiently prolonged, become a cause of sleep. Prisoners upon the rack have slept through sheer exhaustion while undergoing the horrors of torture. Little children frequently fall into a deep sleep immediately after painful, though comparatively bloodless, surgical operations performed without an?sthetics. The depressing emotions, even, may so fatigue the brain as to induce sound sleep through reaction from previous excitement. Every wearied portion of the body must rest; and when the brain thus rests, sleep is the consequence.

Impressed by the force of such considerations, certain physiologists[18] have reasoned from the analogies suggested by a study of the results of muscular fatigue, and have suggested an hypothesis accounting for the occurrence of sleep by a supposed loading of the cerebral tissues with the acid products of their own disassimilation during wakeful activity. The acid reaction of the brain and of the nerves after exertion, corresponding with the development of acids in the muscular tissues during contraction, suggested the probability that an excessive presence of lactic acid and its sodic compounds might be the real cause of cerebral torpor and sleep. Could this hypothesis be proved, ordinary sleep would take its place along with the states of unconsciousness induced by an?sthetics and hypnotics, and the lactate of sodium should be found the very best of medicines for the relief of wakefulness. Its administration for this purpose, however, has yielded only the most discordant and unsatisfactory results. The fatigue theory, moreover, is insufficient, since it furnishes no explanation of the invincible stupefaction produced by cold, nor does it render intelligible the unbroken sleep of the unborn child.

Far more comprehensive is the hypothesis advanced by Pflüger.[19] According to this view, the state of wakefulness is maintained by a certain degree of activity in the cortical substance of the brain. Like all other bodily organs, this substance is renovated by the assimilation of nutrient materials derived from the blood. By this process oxygen is stored up in chemical combination, forming "explosive compounds," whose precise composition is not fully understood. When for any reason the supply of oxygen is insufficient, as in hemorrhage, producing cerebral an?mia, or in impregnation of the red blood corpuscles with carbonic oxide or chloroform, or other substances capable of excluding oxygen from the hemoglobin of the corpuscle, the cerebral tissues are imperfectly renovated. The explosive constituents of the cortical protoplasm are then inadequately renewed after mental activity, and the sensitive portions of the brain are no longer fitted to manifest the highest forms of intelligent activity. But, when nothing interferes with healthy nutrition, the requisite degree of instability in the protoplasm of the brain is effected by intussusception of oxygen. Under the influence of the various nervous impressions which reach the brain, the unstable protoplasmic compounds break up into simpler forms. The motion thus liberated by these "explosions" of excitable matter is, in some way at present utterly inconceivable, projected upon the field of consciousness where the mind dwells; and we are thus brought into conscious relation with the external world.

That the capacity for thus signalling across the gulf which divides matter from mind is the result of a certain perfection and complexity of physical structure is rendered probable by the utter failure of the infra-cortical organs alone to impress the conscious intelligence by any amount of independent activity. The same thing is also indicated by the unconscious sleep of the rudimentary f?tal brain, and by the brevity of the intervals of wakefulness which mark the life of the new born babe. That this capacity is dependent upon a special mobility of the atoms of the brain, is shown by the speedy cessation of intelligence which follows great reduction of temperature, as in hibernation, or during exposure to severe frost. That its exercise is largely dependent upon the activity of the senses is proved by interference with their function, as in the case above quoted (see p. 18) from the observations of Strümpell.

The dependence of the waking state upon the presence and activity of a sufficient quantity of a peculiarly unstable form of protoplasm in the brain is an hypothesis which presents no great difficulty of comprehension. But how may we explain the lapse from the intelligent vivacity of that waking state into the unconscious inactivity of sleep? I have elsewhere[20] discussed the manner in which artificial sleep is produced by impregnation of the brain with an?sthetic substances that interfere with sensibility, and finally produce stupefaction, by hindering the normal processes of intra-molecular oxidation in the protoplasm of the nervous tissues. The same general line of argument may be extended to cover the action of every narcotic agent with which the living substance of the body may become surcharged. Accepting, then, the hypothesis advocated by Obersteiner and Preyer, it becomes an easy thing to account for the gradual onset of sleep by supposing an accumulation of the "fatigue producing" products of intra-molecular oxidation. But we cannot thus explain the rapid and, as it were, voluntary passage from wide awakefulness into a condition of deep sleep, such as may be commonly observed among sailors and others who have formed the habit of going at once to sleep at regularly recurring hours of the day or night. Certain writers have endeavored to account for this fact by imagining a special mechanism at the base of the brain (choroid plexuses of the fourth ventricle, etc.,) by means of which the current of the blood through the brain may be voluntarily diminished, with a consequent arrest of conscious activity. But, still adhering to the hypothesis of Pflüger, we shall obtain a clearer explanation of the facts by considering the phenomena connected with the succession of impressions upon the organs of sense. It has been ascertained[21] that such impressions must persist for a certain measurable length of time in order to excite conscious perception. A sound must be prolonged for at least fourteen-hundredths of a second, a ray of light must agitate the retina for about eighteen to twenty-hundredths of a second, an ordinary contact with the surface of the skin must continue from thirteen to eighteen-hundredths of a second, in order to awaken any knowledge of sound and light and tactile sensation. For the simplest act of perception from two to four-hundredths of a second are necessary. It is, therefore, perfectly reasonable to suppose that when the "explosive material" of the brain has been sufficiently "dampened" by the accumulation of acid refuse which accompanies prolonged cerebral effort, the impressions of sense may no longer suffice to excite in the cortical protoplasm vibrations of sufficient length, or following each other in sufficiently rapid succession, to sustain consciousness. The cortex of the brain may then be likened to a body of water into which bubbles of partially soluble gas are introduced from below. When the bubbles are large, and when they follow each other rapidly, a continual effervescence is maintained upon the surface of the water. But if the size of the bubbles be reduced, or if the solvent capacity of the liquid be increased, the surface will become almost, if not quite, perfectly tranquil. In some such way, without any great danger of error, may we picture forth the manner in which the generation of ideas in the field of consciousness is related to the molecular movements in the space occupied by the protoplasmic substance of the brain. Returning, now, to the rapid induction of sleep, we find that it is usually the experience of people who lead an active life in the open air, and are compelled to endure frequent interruption of their rest. The sailor who is trained to work four hours on deck, and then to sleep four hours below, has been virtually transformed by this habit into a denizen of a planet where the days and the nights are each but four hours long. His bodily functions become accommodated to this condition; his nervous organs store up in sleep a supply of oxygenated protoplasm sufficient only for an active period of four or five hours; so that, when the watch on deck is ended, he is in a state as well qualified for sleep as a laborer on shore at the close of a day of twelve or fifteen hours. Moreover, the majority of those who can thus easily fall asleep are individuals whose waking life is almost entirely sustained by external impressions. So soon, therefore, as such excitants are shut out by closing the eyes in a place of shelter from the sounds and turmoil of the air, comparatively little remains for the stimulation of ordinary consciousness, and sleep readily supervenes through mere lack of cerebral excitement, especially if the excitable matter of the brain has been previously overwhelmed by the products of active exertion.

That analogous, though not identical, predisposition to unconsciousness may also be rapidly induced by modifications of the cerebral circulation is proved by the sudden reduction of cerebral excitability and consciousness which occurs during the act of fainting. In this counterfeit presentment of sleep the important part played by variations of the blood current through the brain is so conspicuous that certain writers have attempted to show that genuine sleep is the result of a diminution in the flow of blood to the cortex of the brain. An ingenious physician has even attempted to relieve insomnia very much as a surgeon might undertake to cure a popliteal aneurism-by placing tourniquets on the arteries leading to the affected part. But the mere fact that syncope produces unconsciousness does not prove that "cerebral an?mia" should be elevated to the rank of the principal cause of natural sleep. The nervous process is the primary factor. The circulation of the blood is everywhere under the immediate control of the nervous system. Consequently, every change in the condition of the nervous structures is followed by a corresponding change in the state of the circulating apparatus. Wherever an organ is aroused to activity, so delicate are the adjustments by which it is connected with the brain and with the heart that it is at once irrigated by an increased flow of blood. When its functional activity subsides, the same mechanism provides for a corresponding reduction in the supply of blood to its tissues. The brain itself forms no exception to this law. This has been admirably shown by the observations of Professor Mosso, of Turin.[22] The learned professor enjoyed the rare opportunity of observing three individuals who had suffered the loss of a considerable portion of the bony walls of the cranium, exposing the surface of the cerebrum, and affording a view of the pulsation of the vessels of the brain. With the aid of the cardiograph, the sphygmograph, the hydrosphygmograph, and the plethosphygmograph, it became possible to register the circulation of the blood in the brain, and to compare that portion of its course with the coincident circulation in other parts of the body. It was thus shown that every increase of emotional or intellectual activity was attended by an increase in the activity of the cerebral circulation. This increase was procured at the expense of other portions of the body, which exhibited a coincident reduction in the amount of blood received from the heart. The occurrence of sleep caused a diminution in the number of respirations, and a fall of six or eight beats in the pulse. The volume of the brain and its temperature were at the same time slightly reduced, through the diversion of blood from the head to other regions of the body. The consequent dilatation of the vessels in the extremities was readily demonstrated by the use of the plethosphygmograph. The extreme sensitiveness of the nervous centers was further illustrated by the fact that if, during sleep, a ray of light were directed upon the eyelids, or if any organ of sense were moderately excited without waking the patient, his respiration was at once accelerated; the heart began to beat more rapidly, the vessels of the extremities contracted, and the blood flowed more freely into the brain. Similar results accompanied the act of dreaming. The return of full consciousness on waking was followed by an immediate increase in the activity of the intra-cranial circulation.

The extreme susceptibility of the brain to influences proceeding from artificial disturbances in the circulation, was exhibited in the case of one of Professor Mosso's patients. By compression of the carotid arteries, unconsciousness was induced, and an attack of convulsions was aroused. In no other part of the body can a corresponding disturbance of function be so quickly produced by similar means. A limb may be rendered bloodless for nearly half an hour, by the application of an elastic bandage, and yet its sensory nerves will remain capable of transmitting impressions from the periphery. But in this case, compression of the carotids for only eight seconds was sufficient to abolish consciousness and to excite convulsive movements.

In all such observations it is worthy of note that the nervous impression is the primary event so long as artificial disturbances are not intruded. The changes of blood-pressure and circulation were invariably secondary to the excitement of nerve tissue. Sleep, therefore, must be regarded as the cause, rather than the consequence, of the so-called cerebral an?mia which obtains in the substance of the brain during repose. This condition of "an?mia" is nothing more than the relatively lower state of circulation which may be remarked in every organ of the body during periods of inactivity. Every impression upon the sensory structures of the brain occasions a corresponding liberation of motion in those structures. The movement thus initiated arouses the vaso-dilator nerves of the cerebral vessels and excites the vaso-constrictor nerves of all other portions of the vascular apparatus. Hence the superior vascularity of the brain so long as the organs of sense are fresh and receptive. Hence the diminishing and varying vascularity of the different departments of the brain as sleep becomes more or less profound. These modifications of the brain and of its circulation are well illustrated by the effects of a moderate degree of cold applied to the cutaneous nerves of the body, as not unfrequently happens when the night grows cool towards morning. The disturbance of the sensitive nerves of the skin is transmitted to the brain. The excitement of this organ causes dilatation of its vessels, and increased irritability of the cortical instrument of perception. This becomes the starting point for the projection of impulses upon the field of consciousness, producing dreams, or even a complete awakening from sleep.

The cause of sleep must, therefore, be sought in the molecular structure of the brain, rather than in fluctuations of the blood-current. In the present state of our knowledge it must be negatively represented as the consequence of a deficiency in the amount of movable oxygen in the nervous tissue. This deficiency may be the result of immaturity, as in the f?tus, or in the new-born infant; or it may result from the accumulation of an excess of the waste-products of intra-molecular oxidation during functional activity-products which hinder the further passage of oxygen into stable combination with the oxidizable elements of protoplasm. Sleep thus produced differs from the artificial sleep induced by narcotic drugs, in the fact that its cause is self-generated by the instrument of thought, while narcotic stupor is caused by the intrusion of substances derived from without-substances which, like the natural refuse of the living cells, more or less completely hinder the processes of oxygenation and oxidation within the tissues of the body. Hence the states of healthy sleeping and waking must necessarily be self-limited and regularly successive; while the state of narcotism is purely accidental, and its duration exactly corresponds with the variable length of the period during which the body may remain impregnated with the hypnotic agent.

Certain morbid forms of sleep further illustrate its dependence upon the persistence of depression in the functional activity of the brain. For some persons this seems to constitute their normal condition. They are either excessively fat, red-faced, and soaked with beer, or they are pale, an?mic, and pulpy, with flabby muscles and a feeble circulation. They fall asleep whenever left to themselves, and never seem to be fully aroused to active life. The fat boy who figures so amusingly in The Pickwick Papers, furnishes a life-like picture of this variety of somnolence.

The introductory stage of the eruptive fevers is often characterized by somnolence. It also frequently appears as the forerunner of coma in the various diseases which terminate in unconsciousness and death. A singular example of this has been observed among the negro inhabitants of the Atlantic coast of tropical Africa. The disorder is known to English writers as sleeping dropsy; by the French it is called maladie du sommeil. It is characterized by daily paroxysms of somnolence which tend to become more and more continuous and profound until they are finally merged in fatal coma. For our knowledge of the disease we are chiefly indebted to the description by Clark,[23] an English surgeon who practised in Sierra Leone, and to the monograph by Guerin,[24] a French naval surgeon, who had enjoyed exceptional opportunities for observation among the laborers who had been carried from Africa to the island of Martinique. Similar cases have been occasionally reported in other regions of the world, but it is among the Africans that it has been principally remarked. The onset of the malady is gradual, commencing with a slight frontal headache. After a few days a disposition to sleep after meals is noted. This becomes increasingly urgent, and the intervals of sleep are prolonged until at length the patient becomes continually soperose. The waking periods are marked by a sluggish state of the intellectual faculties. The pulse is not accelerated, and it remains full and soft. The veins of the sclerotic are turgid, and the eyeball seems unusually prominent. The temperature does not increase, but rather tends to diminish its figure. The skin is dry and moderately cool. The tongue continues moist, and is covered with a white fur. The bowels and the bladder are regularly emptied, and the appetite persists with considerable vigor. Finally, the patient becomes completely comatose, and dies quietly. Sometimes, however, the evolution of the disease is less tranquil. Epileptiform convulsions, followed by progressively deepening periods of coma, interrupt its course, and a continuous muscular agitation marks the closing scene. At the same time the pulse grows weaker and more frequent until its movements cease in death. Recovery is almost unknown, though the duration of the disease often varies from three months to a year or longer. Examination of the body after death yields very negative results; the sinuses and larger vessels of the brain are engorged with blood, but no evidence of inflammation is anywhere apparent. The other organs present no pathological alterations whatever. These observations seem to indicate that the disease originates in some form of general blood-poisoning, rather than in any local inflammation or degeneration. Dr. Clark has called attention to an enlargement of the cervical glands as a feature of the malady. According to Dr. G. H. Bachelder,[25] the native physicians cure the disease by extirpation of the affected glands. He has also observed an initial lesion in the nasal mucous membrane. If this be confirmed, the malady will take its place among the forms of somnolence produced by infection of the blood.

Between the profound unconsciousness of natural sleep and coma may be placed the distinction that the one is always the consequence of healthy physiological processes, while the other is always the result either of injury, of disease, or of some form of intoxication. Comatose unconsciousness may be the result of cerebral compression caused by injury of the head, or by the presence of an inflammatory exudation. Intra-cranial tumors, embolisms, thrombi, diseases of the cerebral arteries, and degenerations of the brain,-in short, every morbid change of which the liquids and the solids within the cranium are capable-may become the cause of coma. Tox?mic conditions of the circulating fluids of the body may benumb the brain with comatose sleep. Few diseases, therefore, exist without the possibility of coma as one of their consequences-a coma which, however, must not be confounded with the genuine sleep which sometimes occupies the larger part of convalescence from acute illness. During such convalescence there is a reversion to the infantile type of nutrition with all its need of prolonged and frequent periods of repose. Like normal sleep, the comatose condition admits considerable variation of intensity. The patient may sometimes be partially roused, as from the coma of alcoholic intoxication, and he may finally recover complete consciousness; but very often the reverse is the fact. The coma deepens into paralysis of the respiratory centres, and death concludes existence without the slightest manifestation of sensibility or intelligence.

Lethargy is a pathological variety of sleep, in which the repose of the body is even more complete than in coma. The victim of coma often presents a countenance suffused with blood; the pulse beats vigorously, and respiration may become stertorous. But in lethargy the abolition of bodily movement is almost absolute. In the milder forms of this disorder the patient may be partially roused, so as to attempt an answer when addressed, appearing like a person in very deep sleep; but in the majority of cases he remains insensible, unconscious, and utterly irresponsive to ordinary forms of irritation. Respiration and circulation are reduced to a minimum, and may, even for a time, become imperceptible. Uncomplicated with hysteria, the disorder is rapidly fatal, but, according to Rosenthal,[26] hysterical lethargy is never mortal.

Many examples of this disease have been afforded by the records of apparent death. I am well acquainted with a lady who, in early childhood, had been laid out for burial at the supposed termination of some infantile illness. Her mother alone insisted that the child was still alive. After some time spent in weeping and expostulation, she applied a blister to the thorax of the babe. This soon excited evidences of painful irritation, followed by a complete recovery. Still more instructive is the case, narrated by Rosenthal,[27] of a young woman, twenty-four years of age, who, in consequence of violent emotional excitement, became unconscious, and presented no signs of life, though tested by placing a mirror before the mouth, and by dropping melted sealing-wax upon the skin. On raising her eyelids, the pupils gave no reaction to light; the limbs remained perfectly flaccid, and the radial arteries were pulseless. Careful auscultation, however, detected a very feeble and intermittent sound in the cardiac region. The walls of the chest exhibited no movement, but the lateral surfaces of the abdomen presented a slow and almost imperceptible oscillation. Gentle faradization of the muscles and nerves of the face, arm, and hand, excited definite muscular contractions. By this method Rosenthal became satisfied that, although the patient had remained for thirty-two hours in this condition, she was only apparently dead. In fact, after continuing forty-four hours in a state of suspended animation, she awoke spontaneously, made a rapid recovery, and seemed to enjoy as comfortable health as an excitable, nervous temperament would permit.

Certain authors make a distinction between lethargy and apparent death; but the difference is one of degree rather than of kind. The movements of respiration and of circulation, though greatly enfeebled, are readily observed in ordinary forms of lethargy; but in apparent death the pulse can no longer be discovered, and nothing more than the faintest sound can be distinguished in the region of the heart. It, therefore, becomes important to have within reach a crucial test of the persistence of general vitality. Such evidence, according to Rosenthal, is furnished by the faradaic current. Within two or three hours after actual death, the muscles cease to respond to the induced current; but in apparent death this form of electro-muscular contractility never disappears. Every other test that has been proposed has failed under certain circumstances. Observation of the changes in muscular temperature during electrical excitation is a method better adapted to the laboratory than for clinical practice.

Lucid lethargy.-In certain cases of apparent death the patient exhibits all the external appearance of suspended animation, but the power of conscious perception does not cease. The senses of sight and hearing remain, and are, perhaps, intensified by inhibition of the power of voluntary movement. The sufferer sees and hears; perception, emotion, memory, the power of reasoning, judgment, volition, all persist. Only the power of executing voluntary movements is lacking.

The victims of this variety of apparent death are usually women, or men who are characterized by a feminine nervous organization. Great mental excitement, fatigue, semi-starvation, and exhausting diseases, are the principal exciting causes of the event. The following case, related by my friend, Dr. P. S. Hayes, of Chicago, illustrates the phenomena of lucid lethargy. The patient was a female physician, about thirty years of age, unmarried, and consumptively inclined. During the course of a long and wearisome hospital service, she was prostrated with typhoid fever. Placing herself under the immediate care of my informant, she was also attended by several of the most eminent physicians in the city. After a long and exhausting illness she appeared to be dying. In the presence of her physician, and surrounded by her relatives, she ceased to breathe. The pulse stopped, life seemed to have gone out. Bottles of hot water were applied to the limbs, and various restoratives were employed. After a considerable time she began again to breathe, and a gradual recovery followed. During the whole time of apparent death, consciousness had been preserved. She seemed to be looking down from a point above her bed; she could see the doctor feeling for her pulse, and was grieved by the sorrow of her friends. Ordinary sensation was temporarily suspended, and she could not distinguish the contact of the hot-water bottles that were applied to her limbs, though actually scalded by their excessive heat. Borne upon the wings of an excited imagination, she thought herself permitted to look into heaven, but was not suffered to enter its gates. In this exaltation of the imagination the reasoning faculties also shared, so that certain philosophical problems which had previously baffled her intellect were now perfectly comprehensible, and the memory of their solution persisted after recovery.

Many similar narratives have been duly authenticated, but the limits of the present chapter will not permit a discussion which properly belongs to an investigation of the phenomena of trance. The important fact for present consideration is the persistence of conscious life, despite the appearance of death. In this preservation of consciousness, notwithstanding the temporary suspension of certain kinds of sensibility and the power of voluntary motion, may be discovered a relationship between the phenomena of lucid lethargy and various disturbances of sleep, which will be considered in a succeeding chapter.

* * *

Sleep, gentle sleep,

Nature's soft nurse, how have I frighted thee

That thou no more wilt weigh mine eyelids down

And steep my senses in forgetfulness?

-King Henry IV, Second Part.

We have seen that the condition of normal sleep is determined by a peculiar molecular state of the substance of the brain-a modification regularly alternating with that by means of which the condition of wakefulness is sustained. We have also seen that sleep is liable to variations in its intensity, and that its course may be partially interrupted by dreams, or even by a more or less complete resumption of the movements of locomotion, constituting the different varieties of somnambulism. Our attention must now be directed to the consideration of those greater disturbances of sleep which either serve to prevent its full development, or else to actually interrupt its course, rendering it incomplete and fragmentary, or even abolishing it altogether. But, inasmuch as the healthy brain, when associated with a healthy body, can only by an extraordinary effort of the will be kept awake beyond a certain period, and then only for a short time beyond the ordinary interval of wakefulness, it follows that the study of the usual causes of insomnia must be an investigation of morbid conditions of the bodily functions. Sleeplessness, therefore, must result, 1st, from a disturbance of the peripheral sensory organs of the nervous system; 2nd, from disordered conditions of the sensory nerves and nerve tracts; 3rd, from morbid states of the brain; 4th, from any or all of these conditions operating in association with each other. We may, therefore, consider, I, Insomnia caused by irritation of the peripheral portions of the sensory apparatus; and, II, Insomnia caused by morbid states of the central nervous organs.

I. Insomnia caused by irritation of the peripheral portions of the sensory apparatus.

Irritation of the sensory apparatus may be ranked in three classes:

1. Affections of the organs of special sense.

2. Affections of the nerves of common sensation.

3. Affections of the sympathetic nerves.

1. Affections of the organs of special sense.-Prominent among these is the effect of light upon the eye. The darkness of night favors sleep; the presence of light hinders its incidence and renders it less profound. During the gloom of a total eclipse animals seek their shelter; birds hide themselves in their nests; domestic fowls arrange themselves upon the roost, and seem quite disconcerted by the speedy return of sunlight. Children often find it difficult to sleep in an illuminated room. I have known nurses who would sit with a wakeful infant under a powerful gaslight till after midnight, and then would express their surprise that the baby persisted in gazing at the flame instead of going quietly to sleep. The inhabitants of Northern Europe find it necessary to darken their sleeping rooms during the long polar day; and travelers in such regions often suffer for want of the natural sleep which only darkness affords. Judge Caton, writing of his travels in Norway[28] says: "We longed for darkness and for night. Do what we could to darken the windows to keep out the light, still it was not night as nature makes it, and which the habit of a lifetime had rendered necessary to sound repose. Artificial darkness, especially when incomplete, is as far from night as artificial light is from day.... These sunny nights can hardly conduce to health, they steal away so much of sleep. One does not readily get sleepy in the sunshine, and then we are so apt to forget to look at the watch to see if it is time to retire."

In the tropical regions of the world it is usual for the inhabitants to sleep during the middle of the day; but they take great pains to exclude the light from their houses during the hours of sleep. The Pacific Islanders cover their faces with the bed clothes for the purpose of excluding the light while attempting to sleep. Repose thus obtained in the daytime often serves to convert the night into a season of wakefulness. The Africans sleep and dream away the heated hours of the day, and give up considerable portions of the night to festivity in the open air-a practice which undoubtedly contributes to the permanence of an inferior grade of social life.

Sudden illumination of the sleeping room will frequently awaken the sleeper. During the great fire in Chicago, A. D. 1871, many persons were thus aroused from their slumbers as the flames lighted up the streets adjoining their houses. One of my acquaintances was awakened one night by a flash of light from the lantern of a burglar who was moving noiselessly about her chamber. The experience of almost every one will testify to the effects of sheet-lightning silently illuminating the sky by night. Dreams, also, are not unfrequently excited by the incidence of light upon the closed eyelids.[29]

The sense of hearing is one of the most persistent of the special senses during the incidence of sleep. It is perhaps the most excitable of these senses during the period of repose. Long after the subject has become immersed in sleep his auditory apparatus remains sensitive to sounds. Dreams are often produced by impressions upon the ear. Often in sleep it seems as if the sense of hearing remained wakeful and watchful for expected signals, as when an alarm clock serves to arouse the sleeper at an appointed hour. Sometimes the sleeper may be shaken and tumbled about in his bed without waking, but if he be addressed by name he will usually reply. It is scarcely probable that the auditory apparatus is any more wakeful than other portions of the nervous system, but its external portions remain during sleep more completely exposed and adapted to the reception of impressions than is possible for the eye and for the organs of touch and taste.

The persistent sensitiveness of the ear during sleep is not so much a capacity for noticing sounds as a sensibility to variations in sonorous impressions. Thus a steady and monotonous noise may, if long continued, serve to render one sleepy; but the sudden cessation of the same sound will awaken every one. Slowly lulled to sleep by the incessant rumble of the engine upon one of the old-fashioned Long Island Sound steamboats, how immediate the awakening of a whole cabin full of people, when the wheels were suddenly stopped! A recent traveler in Guiana[30] relates a curious experience with an Indian magician who undertook to cure him of a slight headache and fever. The method of cure consisted in placing the patient at night in his hammock, while the magician kept up a hideous succession of yells and shouts, shaking the walls and roof of the house with an uproar which never ceased for six hours. Before long the patient passed into a kind of fitful sleep or stupor, during which he seemed to be suspended in a surging ocean of sound. When the noise died away, as if growing fainter in the distance, he would rouse up into a semi-conscious state, but when it again increased he would fall back into stupor. At last, when the noise finally ceased, he awoke completely, but without the slightest relief from headache-an experience quite illustrative of the manner in which the brain may be affected by sound.

It is not often that the sense of smell becomes the avenue of impressions that interfere with sleep. So different are the capacities of individuals in this particular that an odor which might severely annoy one person, would pass almost unnoticed by another. Large cities are sometimes invaded by overwhelming stenches from the various factories which spring up in their neighborhood. While it is seldom true that the vapors discharged by such establishments are directly deleterious to health, they may become indirectly a cause of ill-health through the wakefulness occasioned by them among weakly invalids. The smell of smoke in a bed-chamber sometimes serves to awaken a sleeper, giving warning of the outbreak of a fire in the building. Less energetic odors may disturb the depth of sleep without actually waking the patient. Thus Maury records[31] that when he was made to inhale the vapor of cologne water while asleep, he dreamed of being in the shop of a perfumer.

Excitement of the sense of taste would, doubtless, operate in a similar manner; but it is so difficult to arouse this sense without at the same time irritating the nerves of common sensation about the mouth, that very little can be said regarding the matter. Dreams of gustatory sensations are usually of subjective origin, dependent upon some reflex movement, or upon some agitation of the organ of memory, within the brain.

If, with Sir William Thompson,[32] we recognize a sixth sense-the sense of temperature-it must be admitted that through the varying sensations of heat and cold, sleep can be greatly disturbed. Every one will recall to mind the story told by Dugald Stewart, of a gentleman who dreamed of walking over heated lava on Mt. ?tna when a bottle of hot water was placed against his feet, in bed, on account of some slight indisposition. The temperature of the air is one of the most important factors in the determination of sleep. A high temperature keeps every one awake-a fact well known among the unfortunate denizens of the garrets in our great cities. Not only is wakefulness the direct result of heat, but it is aggravated and embittered by the accompaniments of a torrid climate-insects, foul air, and cutaneous disorders. In the East Indies, so difficult is sleep under such conditions that the wealthy inhabitants compel their servants to cool them all night with the punkah, a large, swinging fan, suspended above the bed, and kept in motion by means of a cord leading outside of the bed-room to the verandah, where the punkah-wallah sits and pulls the string while his master sleeps. So powerful is the force of habit in the organization of the automatic apparatus of the body that, though these punkah-pullers often fall asleep, they still continue, without interruption, the successive movements by which the fan is kept in operation.

The evil effects of a high temperature are greatly aggravated by the presence of humidity in the atmosphere. Dampness interferes with the process of exhalation from the surface of the body, which, consequently, tends to become overheated. The tissues, under such circumstances, are imperfectly defecated, and rapidly pass into a condition of imperfect nutrition. This depresses all the functions of the body, and renders the nervous system inordinately irritable. Sleep cannot be profound and refreshing, because of the over-excitable state of the brain. During the long, hot season in tropical countries, it often becomes necessary to seek a temporary retreat among the highlands and mountains, in order to find a climate sufficiently dry and cool to furnish the condition for refreshing sleep. For the same reason many of the inhabitants of the Southern United States are forced to spend the summer months in the invigorating atmosphere of Minnesota and Northern Michigan. One of the most delightful of experiences may be procured on any warm day in summer by embarking, at Chicago, upon one of the steamboats bound to Mackinac. At the wharf, in the hottest and dirtiest part of the city, all is dust, perspiration, and discomfort. The wide cabins are filled with people who are tired, thirsty, and discouraged. Sickly, squalling babies swarm in numbers sufficient to drive one mad. As the sun goes down, the signal-whistle sounds, head-lines and stern-lines are quickly cast off, the propeller churns the mire behind the boat. Slowly swings the huge fabric away from the shore, gliding between the walls of sun-scorched brick that line the stream on either side. At last the light-house at the mouth of the river is passed, and we are out upon the blue waves of Lake Michigan, with a heavenly breeze searching every crack and cranny of the hull. New life animates every form, and presently a great silence pervades the brilliant cabins. The children have left their woes behind, and, for the first time, in many weeks, perhaps, they and their weary mothers sleep the sleep of innocence and peace.

The dependence of a high atmospheric temperature upon the direction of the wind renders the course of the aerial currents a matter of great importance in relation to sleep. The southerly winds which, in the northern hemisphere, are hot and enervating, always produce an increase of wakefulness. The winds that blow from the heated deserts of Africa, Arabia, and Australia, are greatly dreaded upon this account, as well as for the other numerous discomforts which fly in their train. Their cessation, and their replacement by a cool, polar current brings relief at once. The changes thus produced in the electrical condition of the atmosphere doubtless contribute more than is usually known to these results. A cloudless sky gives evidence of positive electricity, which is much stronger in winter than in summer.[33] Clouds are sometimes positive and sometimes negative. According to Fonssagrives[34] the atmospheric electricity is positive during northerly winds, and negative during the prevalence of winds from the southerly quarters of the horizon. Great disturbances of the electrical condition of bodies is often observed during the occurrence of the sirocco in North Africa. Arago has related the case of an officer in the French army[35] who saw sparks of electricity leaping from his epaulettes at every blast of the sirocco encountered on a march in the neighborhood of Algiers. Such atmospheric disturbances often produce very disagreeable effects upon persons of a nervous temperament. According to Fonssagrives (loc. cit.) such patients frequently experience, during the prevalence of storms which traverse great distances, a high degree of insomnia, together with headache, pains in the limbs, joints, and old injuries, and a general indefinable sensation of discomfort. S. Weir Mitchell has carefully traced the connection between these phenomena and the variations of barometric pressure which accompany the revolving storms that cross the continent in a northeasterly direction.[36]

Though the effect of a high atmospheric temperature is unfavorable to sleep, an excessive temperature produces the opposite condition. Stupor rather than sleep is the consequence of insolation and of exposure to great heat from artificial sources. This is a pathological process, and, therefore, must not be mistaken for natural sleep. It may result either from cerebral congestion, or from cardiac exhaustion, and is characterized by an extraordinary bodily temperature and a high rate of mortality.[37] So elaborate are the arrangements for the preservation of a uniform temperature throughout the body that it is practically impossible for a sunstroke to occur unless the regulative apparatus has been previously deranged by ill-health.

Excessive cold operates in like manner to produce a condition of stupor that tends to a fatal termination. But moderate degrees of cold act as excitants of wakefulness. By effecting a contraction of the vessels of the skin cutaneous circulation is impeded. The venous side of the circulatory apparatus becomes overloaded with blood; the exhalation of carbonic acid and the production of heat are reduced. The discomfort that results from this disturbance of the natural functions of the tissues is sufficient to arouse the brain to wakefulness, just as an imperfect oxidation of the blood serves to excite the respiratory centre in the medulla oblongata. It is hardly necessary to allude in this connection to the increased flow of blood through the brain occasioned by this as by every other excitement of the sensorium. Local refrigeration of any portion of the body thus acts as a painful excitant of the cerebrum, and produces wakefulness, very much as distention of the intestines with gas will keep one awake. It is for this reason almost impossible to sleep with cold feet. Conditions of this sort are pathological, and are far in excess of the agreeable coolness which favors sleep. The effects of progressive diminution of the temperature of the air are well illustrated by the hibernation of animals.[38] As the temperature of the air diminishes, in winter, animals like the marmot fall into a species of sleep. Their movements of respiration and circulation are greatly reduced, and their bodily temperature falls, though it always remains several degrees above the temperature of the surrounding air. So long as the average degree of cold is maintained, the little creature sleeps naturally; but, if the air becomes extraordinarily cold, the physiological repose of the animal is disturbed. It becomes uneasy, wakes up, and seeks a warmer retreat. Too great a degree of cold thus becomes a cause of wakefulness. If the animal under these circumstances fails to secure protection against a falling temperature, it passes into a state of lethargy that is often fatal-a pathological condition being substituted for the physiological sleep of ordinary hibernation. In like manner the human animal may experience the threefold effects of refrigeration: first a pleasing coolness that favors sleep; then an uneasy sensation of cold which causes wakefulness; and, finally, a lethargy that paralyzes all the functions of the body and terminates in death.

2. Affections of the nerves of common sensation.-Chief among the causes of sleeplessness thus produced is pain. This is a modification of feeling, caused by excessive or extraordinary excitement of the peripheral nerves of sensation. The seat of the excitement may be in the skin or in the deeper tissues of the body. Cutaneous pain may be caused by the activity of various insects, like flies, mosquitos, fleas and bedbugs, or by the presence of certain parasites, such as the itch-mite, or by ordinary diseases of the skin, of which notable examples are found in erysipelas, erythema, urticaria, lichen, prurigo, certain varieties of eczema and psoriasis. The troublesome forms of pruritus which accompany icterus, or which may occur without any clearly defined cause, are frequent causes of wakefulness. The last mentioned disorder must, however, be sometimes recognized as a consequence of central nervous disorder, rather than a result of peripheral disease. Witness the frightful itching sometimes experienced during the progress of chronic myelitis. All kinds of injuries, wounds, ulcers, and other local inflammations are common causes of insomnia by reason of the painful impressions transmitted from them to the brain. Hence the great importance of anodynes and hypnotic remedies in the course of surgical practice. Diseases or injuries of the various peripheral nerves are notable causes of sleeplessness. Witness the horrible wakefulness caused by neuritis and by neuralgia. The development of neuromata in the stumps of amputated limbs may thus become a most painful cause of insomnia. Inflammations which encroach upon sensitive nerves produce intense pain with consequent loss of sleep. Of this very conspicuous examples are furnished by spinal meningitis, and by the effects of local periostitis causing compression of the branches of the fifth pair of nerves.

3. Affections of the sympathetic nerves.-So much still remains to be learned concerning the pathological functions of the sympathetic nerves that it is impossible to assign with any great degree of precision the exact amount of interference with sleep that may depend upon disordered conditions of this portion of the nervous system. Since their principal functions consist in the regulation of the flow of blood and lymph throughout the body, and in the control of the processes of nutrition, calorification, secretion and excretion, it follows that any considerable derangement of their healthy action must be represented by a corresponding disturbance of the brain. This may reach the field of consciousness in the form of pain, and thus may become a cause of sleeplessness. In all the phenomena of inflammation sympathetic nerves play an active part. In certain portions of the body, as in the principal viscera, and in the periosteal covering of the bones, they are the interstitial nerves of the structures. When the body is in a healthy condition these nerves convey impulses of a sensory character which do not reach the cerebral organ of conscious sensation. But in certain morbid states they become inordinately sensitive, and they then serve to convey and probably also to magnify sensations to an extent that may cause exquisite pain with all its consequences. Witness the pain experienced during the various forms of colic. Rheumatic inflammations, pleurisy, pericarditis, peritonitis, cystitis, metritis, ovaritis, gastro-enteritis, and other similar diseases owe their principal suffering to the affection of the sympathetic nerves connected with the respective organs which become the seat of pain. Including with the sympathetic nerve the pneumogastric nerve, which occupies a functional position between the strictly peripheral and the ganglionic nerves, all the various forms of pain and uneasiness experienced in the region of the heart and of the lungs may be assigned to this system of nerves. Thus the various species of respiratory disturbance, such as asthma and dyspn?a from any cause, and the forms of palpitation and other cardiac disorder may become causes of wakefulness. In like manner the vague and uneasy sensations associated with certain varieties of dyspepsia are frequent sources of sleeplessness, not merely by reason of the pain which they occasion, but also because of the general disorders of nutrition with which they are associated.

II. Insomnia caused by morbid states of the central nervous organs.

So intimately connected are the spinal cord and the brain that their disorders may properly be considered together. These may be classified as:

1. Disorders of circulation and nutrition.

2. Inflammations and degenerations.

3. Neoplastic encroachments.

Disorders of circulation and nutrition.-Hyper?mia of the brain is a frequent cause of wakefulness. This may be maintained by an unconscious effort of the organ of the will under the influence of any great and unusual excitement of the mind. So soon as the mental excitement is allayed, the excessive afflux of blood subsides, and the brain becomes fitted for sleep. But, if excitement be too far prolonged, the nutrition of the nervous centres suffers, and the regulative apparatus of the cerebral circulation becomes exhausted, so that the brain cannot rest, because its inhibitory centres have lost their power of control over the lower ganglia of the organ. The cerebro-spinal centres are then in a condition analogous to that of a locomotive engine on which the engineer can no longer regulate the production and distribution of steam. Such a condition is usually the result of numerous antecedent causes. Long hours of work, scanty or improper food, insufficient sleep, bad hygienic surroundings and habits, with indulgence in the use of narcotics and stimulants, are among the most common causes of the disorder.

Active hyper?mia of the nervous centers has been above mentioned as the consequence of cerebral function under unfavorable conditions. But, as the disorder persists, its type undergoes a change. We still speak of the disorder as functional in its character, but it continually tends to become organic. No visible alterations, perhaps, can be detected, but, evidently, there are radical changes in the substance of the nervous tissue. Nutrition suffers throughout the body to a degree that attracts attention. The blood diminishes in quantity and quality, till the patient becomes notably an?mic. In this condition the brain is inordinately excitable. It is incapable of sustained activity, and the patient may even be oppressed by an inclination to constant drowsiness; yet he will be unable to sleep soundly, and his sleep will be continually agitated by dreams. This state is one of the constant accompaniments of slow starvation. The molecular structure of the nervous organs seems to be so slightly constructed, under such circumstances, that its equilibrium is disturbed by the most trifling incidents. It may be likened to a lofty wall of bricks laid up without mortar-"if a fox go up," the entire structure may be thrown down with a tremendous noise. Thus the an?mic and irritable brain will react excessively under the slightest impression; consciousness is invaded by perceptions which would never arise under normal conditions of the nervous tissue; and the mind is continually aroused. This form of wakefulness is very frequent among women who have become an?mic, and among patients who are slowly convalescing from exhausting diseases.

It is impossible in every instance to decide whether a given state of wakefulness is the result of cerebral hyper?mia or an?mia. In the one case the persistence of wakeful activity of the mind is due to excitement of the cerebral cells, accompanied by a lavish irrigation of their substance with the plasma of the blood. In the other case the excitement is occasioned, not so much by increased afflux of the blood, as by a morbid instability of the nervous substance. The outcome in both cases is very similar-mental excitement and wakefulness.

In a third class of cases the agitation of the brain is produced by the direct action of certain chemical agents upon the cortical substance. Tea and coffee are familiar examples of such agents. The caffeine, by virtue of which they produce their effect, when transported to the brain, enters into combination with its protoplasm in such a way as to stimulate molecular movement. Perception is thus quickened, and the mind is aroused. Sleep is postponed until the effect of the stimulant has subsided. This form of wakefulness is quite different from that produced by alcoholic drinks. These operate, when taken in small quantities, to favor cerebral equilibrium-and consequent equanimity-by producing a general dilatation of the smaller blood-vessels. Their an?sthetic influence is favorable to sleep, under such circumstances. But, if frequently repeated, these doses of alcohol modify the nutrition of the nervous system until, at last, a condition of irritable weakness is reached, in which wakefulness of a most distressing character is experienced.

Inflammations, degenerations, and neoplasms.-The early stages of inflammation involving the central nervous organs are marked by that form of insomnia which is associated with active hyper?mia. The headache and painful delirium which accompany the different varieties of meningitis, are causes of a wakefulness that persists until the brain is merged in the coma of compression. The interstitial changes which cause the various forms of insanity, are in like manner causes of wakefulness. Local injuries and degenerations of brain-substance, tubercular deposits upon the meningies, and all the different forms of intra-cranial tumor, are causes of wakefulness, both by reason of the direct irritation which they produce, and by reason of the circulatory disturbances which arise in their neighborhood.

Finally, it must be observed that wakefulness may result from excitement of the brain by irritating substances transported through the blood from distant centers of disease in remote organs of the body, or derived from articles that have been absorbed with the food and drink, or with the air that enters the lungs. Thus wakefulness may accompany cutaneous disorders that interfere with perspiration. Imperfect elimination through the liver, kidneys and intestines, leaves the blood charged with excrementitious substances which arouse the brain to wakefulness. In like manner, various poisons, like lead, arsenic, etc., different miasms of telluric origin, the products of putrefaction, and the various animal contagia, may produce insomnia by their prejudicial effect upon the nutrition of the nervous structures throughout the body.

* * *

O, true apothecary!

Thy drugs are quick.

-Romeo and Juliet.

An occasional attack of wakefulness may fall to the lot of any one as a consequence of the various disturbances of health or equanimity of mind to which all are liable. Occurring as an accident in a state of health, it produces merely a feeling of lassitude and weariness during the subsequent day. This soon disappears, after a night of refreshing sleep, and the subject is nothing worse for the incident. But the recurrence of the disorder is a thing to be deprecated, not only for the reason that it denotes a departure from the physiological order of life, but because its frequent repetition prevents the adequate repair of the tissues of the body. The great function of nutrition suffers as a consequence, and the patient rapidly falls into a condition of premature old age. When this takes place as a result of some temporary error of hygiene, or as a consequence of diseases which admit of successful treatment, the patient may be restored to health by judicious management, but lost youth and elasticity of the tissues can never be fully regained. The most formidable cases of insomnia are those for which no adequate cause can be recognized in the habits, mode of life, and state of health of the patient. Grave and permanent disorder of the brain is then to be feared. Such wakefulness is a frequent precursor of acute meningitis in children and adults. It frequently ushers in the early, insidious, formative stage of tubercular meningitis, and of the infective fevers-notably typhoid fever. It forms one of the most suspicious symptoms among the introductory phenomena of insanity; and during the course of protracted diseases, its intrusion is an omen of most unfavorable augury. It will, therefore, be found useful to consider with some degree of detail the circumstances under which insomnia may occur, and the best means of averting its onset.

A severely logical reference to previous doctrines regarding the condition of the brain during sleep, has led many authors to consider the therapeutical treatment of insomnia chiefly as a matter of modification of the cerebral circulation. Sleep has been supposed to depend upon a comparatively bloodless state of the brain, and wakefulness upon the contrary state. For such theorists the treatment of insomnia consists very simply in the use of agents which are supposed to be efficacious in reducing the flow of blood through the head. Tourniquets, placed upon the carotid arteries, occupy a position of great honor in the armamentarium of such people. Recognizing the fact that changes in the force of the circulation accompany and sustain every change in the activity of the cerebral cortex, we, however, attach the greatest importance to the condition of the nervous substance itself. For a clear understanding of the proper mode of medication, it is important to ascertain whether the cerebral substance is in a state of normal activity, or whether it is in a state of healthy, but excessive, activity, or whether its seeming excitement is merely the result of irritable weakness. Since these opposite conditions may declare themselves during the course of any disease in which insomnia may become a troublesome phenomenon, it is impossible to make a classification of diseases upon the basis of these different states of the brain. It will, therefore, be found more useful to consider the subject of sleeplessness as it ordinarily presents itself during the clinical progress of the several forms of disease. It will, then, appear that the type of insomnia is liable to variation with the course of each individual malady; and its treatment must vary accordingly.

Before proceeding to a discussion of the therapeutics of insomnia in connection with particular diseases, it will be advantageous to pass briefly in review the different remedies which are useful in the treatment of wakefulness. These may be divided into two classes: Nervous stimulants, and nervous sedatives. Among the first may be also reckoned food, heat, baths, and counter-irritants. Like all nervous stimulants, they promote the complete and harmonious action of all parts of the nervous system, favoring that equilibrium of the circulation which is most favorable to the development of sleep. The second class of agents comprises all such remedies as act directly upon the nervous tissue of the brain, depressing its functional activity, and hushing to rest those particular organs which, by their undue excitement, serve to keep the remainder in a state of wakefulness. All these substances produce decided effects upon the spinal cord and the peripheral nerves, but it is their operation upon the brain which principally interests us in connection with insomnia.

Nervous Stimulants. Nervous Sedatives.

Heat.

Baths.

Massage.

Electricity.

Counter-irritants.

Food.

Digitalis.

Camphor.

Musk.

Valerian.

Cannabis indica.

Belladonna.

Hyoscyamus.

Stramonium.

Phosphorus.

Acids.

Opium. Cold.

Alcohol.

Paraldehyde.

Ether.

Chloroform.

Chloral.

Butylchloral hydrate.

Amyl nitrite.

Opium and opiates.

Bromides.

Hops.

Gelsemium.

Conium.

NERVOUS STIMULANTS.

It may at first sight seem to be a contradiction in terms when it is asserted that sleep may result from the administration of a nervous stimulant. This does occur, but only indirectly, and as a consequence of a restoration of energy to those portions of the nervous system which serve to moderate the activity of the organ of the mind-the cortex of the cerebrum.

Heat, for example, is an undoubted stimulant. When added to the body in quantity sufficient to overcome chilliness, it tends to equalize the circulation of the blood, and produces throughout the body a nervous equilibrium that prevents any particular organ or member from arousing the others to wakefulness.

Baths.-The application of heat in the form of a warm bath constitutes one of the most admirable means of tranquilizing the brain. Children who are restless at night are delightfully soothed by a warm bath every night and morning. The water should be of an agreeable temperature-this is better than any exact figure upon the scale of a thermometer-and the bath should not last lounger than ten minutes. Similar baths exercise a happy effect upon adult patients who are moderately feverish, nervous, and wakeful. If strong enough, they may take a full bath at bedtime; but if too feeble to leave the bed, gentle sponging with warm water will prove most refreshing, and will usually be followed by restful sleep. The well-known derivative effects of hot foot baths scarcely need to be more than mentioned in this connection.

Turkish baths form an invaluable adjuvant in the treatment of chronic cases of insomnia arising from rheumatic, gouty, and dyspeptic disorders of the health. The copious perspiration induced by the heated air of the hot chamber is depurative, while the cold douche and the massage with which the bath is concluded have a powerful effect to stimulate all the functions of the body. By this means the brain is enabled to resume a healthier mode of action, and sleep follows as a matter of course.

Massage.-This constitutes a process of rubbing and kneading the body. It has been practiced from time immemorial among the oriental races and the Pacific Islanders as a means of relief from fatigue of every kind. Among the Japanese the practice of massage is a monopoly in the hands of the blind, who are thus enabled to support themselves. Various modifications of the oriental method have been introduced under the names of percussion, shampooing, and the Swedish movement cure. They all possess the common features of friction applied with the hand to the skin, compression of the muscles with the hands, and passive movements of the different articulations of the limbs and body. For effecting all these processes nothing has yet surpassed the Sandwich Island lomi-lomi as practised by the court-retainers of the ancient chiefs. As a means of relieving fatigue, and of removing muscular soreness, after violent exertions of every kind, it is far superior to the imitations performed by European and American professional masseurs and masseuses. Nervous headaches, the pains that accompany spinal irritation, and all conditions of restlessness and wakefulness which depend upon exhaustion are relieved by this method. The well-known soothing influence of a mother's hand stroking the face and forehead of her sleepless child, is an example of only one of the effects thus produced by the skillful masseur. These salutary results must be assigned to the uniform friction of the skin, causing the liberation of heat, and modifying the electrical conditions of the body. By this, the impressions derived from the peripheral nerves are reduced to a more harmonious series. The circulation of blood and lymph is rendered more active in the substance of the muscles, and all the processes of nutrition are thus stimulated to a degree that restores the equilibrium of function throughout the nervous system. Being no longer irritated by suffering portions of the body with which it is connected, the brain then yields to the effects of its own fatigue, and sleep supervenes.

Electricity is chiefly useful in those cases where it is impossible to discover anything but cerebrasthenia as the cause of wakefulness. According to Beard and Rockwell,[39] sleep may result from the use of any one of the different methods of electrization. The passage of a moderate current, either galvanic or faradaic, through any portion of the body often produces a temporary feeling of sleepiness; but the long continued employment of electricity is needful to effect those changes in cerebral nutrition which are necessary for a permanent cure of insomnia. In cases of sleeplessness caused by worry and overwork, great benefit is often experienced from the daily passage of the faradaic current from the back of the neck, or from the pit of the stomach, to the feet. Static electricity, and the electric bath, are also very effective in many cases of so-called spinal irritation and insomnia.

Counter-irritants are substances which are applied to the surface of the body for the purpose of communicating to the superficial sensory nerves impulses (irritation) which may serve to inhibit the morbid functions of distant or central nervous structures. Various explanations of this process have been presented; notably a most ingenious argument by Dr. T. Lauder Brunton[40] in favor of the theory of inhibition by interference of vibrations-impulses from the periphery interfering with vibrations originating in morbid conditions of the central nervous organs-very much as darkness is produced by the interference of luminous undulations, and silence is effected by interference of sonorous waves in the atmosphere. This hypothesis is the one that is most conformable to the present requirements of science, and is hereby accepted as the most satisfactory explanation of the action of counter-irritants.

The drugs in general use for the purpose of counter-irritation are cantharides, capsicum, mustard, thapsia, turpentine, aconite, and croton oil. Cups, leeches, and certain special applications of electricity, also owe much of their virtue to the same power of modifying functions at a distance. Under the influence of all these agents the molecular vibrations of the brain may be profoundly influenced; pain may be annulled, and sleep be procured. The circulation of the blood is so powerfully affected by these measures that their good effects are usually attributed to the circulatory changes thus produced. But, as in all other modifications of the circulation, the nervous tissues and the vascular channels must first be reached by influences unconnected with the blood itself before its current can be diverted from one region to another. The inhibitory action upon the nervous organs is the primary effect. The diversion of the circulation is a secondary consequence, by which, undoubtedly, the degree of nervous change can be estimated, and by which the inhibitory effects in the brain are intensified and sustained.

Food.-In a considerable number of cases of insomnia, its cause lies in an irritable weakness of the nervous tissues. Exhausted by overwork, or debilitated by the loss of blood, or half-starved during the course of a long illness like typhoid fever, a condition of wakefulness may be established which will add to the dangers experienced by the patient. In this state there is great restlessness-the sufferer experiences no severe pain, but he cannot lie still. This form of sleepless agitation is often encountered during the later stages of exhausting diseases; and, if not properly treated, it soon leads to a fatal termination. The most important remedy for such distress is found in food. This must be soluble, diffusible, stimulant, and nutritive. Milk, alcohol, eggs, and meat-juice, are the typical representatives of such food. Milk should be as fresh as possible, and should be slightly salted, in order to hinder the formation of hard curds in the stomach. For young children it may be peptonized with advantage by gently heating one pint of milk with five grains of sodium carbonate and five grains of pancreatic extract dissolved in half a pint of water. The mixture may be sufficiently warmed by placing it in a bottle immersed for half an hour in a jug of hot water (Fairchild). By this process the milk is partly digested before it is drank, thus relieving the alimentary canal of a corresponding amount of work.

Furnished in the form of koumiss, milk is not only presented in a digestible form, but the alcohol and the acids yielded by its fermentation are powerful aids to the process of digestion. Fermented milk forms a considerable portion of the daily food of the nomad tribes of Central Asia, and it is highly esteemed among the Russians in the treatment of pulmonary consumption. It is useful in all diseases affecting the digestive organs, and can often be tolerated, even by very young children, when nothing else will remain in the stomach. Considerable mystery is made of its preparation by those who sell it for an enormous price; but its composition is really very simple, and its actual cost is within the reach of every one. The following formula for its preparation has given great satisfaction to many of my patients:

Dilute five quarts of milk with three quarts of hot water. When lukewarm, add half a cupfull of sugar of milk (which can be obtained from any wholesale druggist), and one bottle of well fermented koumiss (or a little yeast). Stir the mixture thoroughly, and let it stand in an open jar, at a temperature of about 72° F., till it begins to curdle. Then stir in half a cupfull of pulverized coffee sugar, and cork tightly in champagne bottles with the best velvet corks. The bottles should be kept quite cool, as fermentation proceeds very briskly, and will break the containers if left in a warm room. A large ice-box is the best receiver during hot weather. The koumiss thus prepared is ready for use at the end of a week. It may be most conveniently drawn from the bottle with a champagne tap. The entire cost of the article need not exceed seven cents a bottle.

Sleeplessness caused by chronic dyspepsia will often yield to a diet of koumiss, when every other remedy has failed. When the stomach is very intolerant, it should at first be taken in very small doses, repeated as often as every hour. It will soon become possible for the same patient to drink two or three quarts each day.

Eggs form one of the most nutritious and easily digested articles of diet. They should be taken uncooked, beaten up with milk to which a small quantity of wine or spirits and sugar have been added. A glass of eggnogg, thus prepared, is invaluable in the insomnia of fevers and other conditions of exhaustion.

Meat-juice can be procured in numerous forms. The various soluble extracts of meat, Valentine's liquid extract of beef, Murdoch's liquid food, all represent the juice that oozes from rare beef. Its nutritive value is not very great, but it possesses considerable energy as a stimulant. Meat juice, therefore, occupies an important place as an excitant of those functions which must be aroused in order to secure the proper digestion of other articles of food. It should, therefore, be administered in connection with them. As the ordinary meat extracts are frequently very unpalatable, they may be administered in fresh broth or soup, to which they give body and energy without unpleasantly affecting their savory taste.

Neurasthenic patients, whose insomnia results from physical exhaustion, should never retire at night without taking some form of light and easily digested food. A simple slice of bread, or a piece of plain sponge-cake, with a glass of koumiss, forms an excellent model for such a meal.

Digitalis is only indirectly useful as an hypnotic. In cases of cardiac disease, with enfeeblement of the heart, dyspnoea, dropsy, and sleeplessness, digitalis is often of the greatest service. It has also been highly recommended in delirium tremens. Administered in the form of an infusion, it has been given in doses of a tablespoonful, every four hours, with apparently good effect. Its use is indicated in cases characterized by weakness of the heart, with a rapid and feeble pulse. Under its influence the state of the circulation improves, delirium ceases, and sleep occurs.

Camphor.-This substance is not an hypnotic, but it forms a valuable addition to various hypnotic compounds. It is a cerebral stimulant, and aids in the establishment of that nervous tranquility which favors the incidence of sleep. It may, therefore, be advantageously associated with opiates in the restlessness and insomnia of exhaustion. Tully's Powder, a valuable substitute for Dover's Powder, contains camphor. This renders it preferable to the ordinary opiates in typhoid fever, and in other exhausting diseases.

Musk, the dried secretion of the preputial follicles of the musk-deer, is a substance which, on account of its high price, is rarely used as an hypnotic. Given in doses of ten grains, every two or three hours, it is exceedingly valuable (Stillé and Maisch) for the relief of "all those nervous phenomena which are represented by the term ataxia, and among them subsultus tendinum, mild muttering delirium, floccitation, musc? volitantes, and hiccough, with a small, frequent, tremulous or irregular pulse, without coma and without collapse. Under these circumstances musk tends to produce refreshing sleep, while it calms muscular spasm and favors perspiration, while the pulse grows fuller, more regular, and less frequent.... In proportion as ataxic prevail over adynamic phenomena is musk advantageous." Such conditions are chiefly encountered in typhus, typhoid fever, the eruptive fevers, and pneumonia. Musk is very efficacious for the relief of "wakefulness resulting from combined mental and bodily fatigue-such cases, in fact, as are benefitted by valerian, camphor, asafetida, and ammonia."

Valerian and its different preparations form a typical class of agents which indirectly favor sleep by their gently stimulant effect upon the brain. They are all useful in quieting that form of hysterical excitement to which women are liable during the "change of life." That form of restlessness, usually resulting from fatigue, in which the patient feels as if she cannot sit still, is often relieved very promptly by the valerianate of ammonia. Wakefulness caused by neuralgic pains, or by exhaustion, often yields readily to scruple doses of valerianate of zinc or ammonia. The elixir of the valerianate of ammonia is a very elegant preparation of the drug.

Cannabis Indica.-A cerebral stimulant which produces, at first, an agreeable exaltation of the mental faculties. This is followed by a condition of delirium, succeeded in its turn by sleep. It is, therefore, impossible to use the drug for merely hypnotic purposes; but it is a useful adjuvant, in small doses, to other hypnotic remedies. Given in doses of ?-1 grain, it may be advantageously associated with opiates, or with hyoscyamus or belladonna in cases which do not easily tolerate the preparations of opium. The tannate of cannabin, given in doses varying from five to ten grains, has been recommended as an hypnotic; but, like the extract from which it is derived, its effects are rather uncertain. The pure alkaloid, cannabin, has been recently introduced as a soporific, in doses of three-quarters of a grain to a grain and a half. According to Stillé and Maisch, the wakefulness caused by the itching of eczema may be relieved by the use of cannabis indica. The uneasy sleep attendant upon ungratified sexual appetite may also be relieved in the same way, since the drug is decidedly anti-aphrodisiac.

Belladonna is not directly hypnotic, unless given in poisonous doses, but its medicinal operation tends to overcome certain conditions that hinder sleep. By its anti-spasmodic effects it relieves many forms of spasm which would otherwise interfere with sleep. Spasmodic asthma furnishes an example of such an affection. This may be relieved by the hypodermic injection of atropine. Whooping cough is another disease which may be largely controlled by the internal administration of the drug, especially by inhalation of a spray that has been medicated with belladonna. Neuralgia, especially the form that involves the head, face, and intercostal nerves, is greatly mitigated by the use of belladonna, or its alkaloid, atropia. Its association with opiates seems to increase their hypnotic effect, while at the same time neutralizing their disagreeable action. According to Curci,[41] it opposes the tendency of opiates to cause cerebral hyper?mia. For this reason it is generally advisable to combine sulphate of atropia with sulphate of morphia for hypodermic use. Of the former 1-100-1-80 grain may be used with ? grain of the latter. Certain patients are exceedingly intolerant of belladonna and its derivatives, a fact that must be kept in mind, especially when using the alkaloid, atropia. Fatal consequences are very rare, but uncomfortable dryness of the throat, dilatation of the pupils, and some degree of delirium are not uncommon. At the same time it must be admitted that in many instances relief from suffering is not obtained until these physiological effects of the drug have been manifested.

Hyoscyamus.-As might be inferred from their close botanical relationship, hyoscyamus and belladonna present many points of similarity. Their alkaloids are almost identical in chemical and physiological properties. The extract of belladonna is considerably stronger than the extract of hyoscyamus. Like other solanaceous plants, this is powerfully narcotic and anodyne. Sleep is produced only by the use of the drug in large doses, which also tend to excite delirium, sometimes even reaching to the height of maniacal fury. Children tolerate hyoscyamus in doses proportionally larger than can be taken by adults. By many physicians it is considered the hypnotic par excellence for children. In the various forms of insanity the tranquilizing influence of hyoscyamus is highly esteemed. The derivative preparations, hyoscyamine and hyoscyamia, are preferable for use in this class of cases. The first may be given in doses of 1-16-1 grain; the latter is much more powerful, and should be given in doses not exceeding 1-100 grain until the degree of its tolerance has been ascertained.

Stramonium.-This is another of the solanaceous plants, possessing many qualities like those found in belladonna. It is not directly hypnotic. Poisonous doses produce delirium and persistent insomnia. But its anti-spasmodic effect upon the paroxysm of nervous asthma renders it indirectly hypnotic in that affection. For the relief of bronchial spasm the smoke of the dried leaves should be inhaled in considerable quantity. It may be smoked in a pipe; or, mixed with saltpetre, it may be made to smoulder upon a tin plate, while the smoke is drawn by inspiration into the lungs. Various kinds of medicated pastiles have been prepared, to effect a similar result by furnishing the drug in a convenient form for use. Tobacco and lobelia operate in a very similar manner upon all spasmodic affections of the respiratory passages; but their energy is almost too great for the comfort of the patient.

Phosphorus.-Bartholow has recommended this drug in "cases of wakefulness dependent on cerebral an?mia and exhaustion," and in "the wakefulness of the aged, accompanied with muscular cramps, feebleness of memory, giddiness, and trembling of the voluntary muscles on exertion." In minute doses, it is true that phosphorus acts as an irritant of nervous tissue. It promotes destructive changes in the tissues of the body, and thus produces a temporary excitement which may favor the processes of nutrition. Indirectly, it may thus prove beneficial in many cases of cerebral exhaustion; but as a direct hypnotic it will be found of very little service. It should be given in doses of 1-100 grain every four hours.

Acids.-In those forms of sleeplessness which are dependent upon disordered conditions of the digestive apparatus, acids are often useful. Their topical effects upon the mucous membrane of the stomach are stimulant and alterative; hence they are useful in atonic dyspepsia, where there is deficient secretion of the gastric juice. In such cases hydrochloric acid and lactic acid are useful. The first should be given, in doses of five drops diluted with half a pint of water, after each meal. Lactic acid may be given in doses of one or two teaspoonfuls, similarly diluted. It has been asserted, on theoretical grounds, that lactic acid and the lactate of sodium are directly hypnotic, but its experimental use has never given satisfactory results. Phosphoric acid has been used in the same way, with very similar effects. An impure solution of phosphoric acid, known as Horsford's Acid Phosphate, has been extensively used for its supposed hypnotic properties. It assists digestion, stimulates the kidneys, and by its general diffusion promotes molecular activity throughout the body. It is thus indirectly beneficial in cases of insomnia. No small part of the benefits thus obtained must, however, be ascribed to the water with which these acids are diluted. When the liver becomes sluggish in its action, nitric acid, in doses of five drops diluted with half a pint of water, may be taken every four hours with great advantage. Thus used, the mineral acids may often yield invaluable service in the treatment of insomnia occasioned by cachectic conditions of the body-notably such as are produced by malaria, oxaluria, and the so-called phosphatic and rheumatic diatheses.

NERVOUS SEDATIVES.

The remedies thus far considered are but indirectly hypnotic in their effects, though exceedingly valuable as agents for the production of conditions favorable to sleep. We may now pass to the consideration of a class of remedies which operate more directly upon the brain to depress its energy. They are, therefore, called nervous sedatives, and they include the majority of narcotic substances.

Cold.-The operation of cold upon the body has already been sufficiently considered. It only remains to note the effects of cold applied through the agency of baths and local refrigerants. A full account of the theory and practice of hydrotherapeutics can be found in the second volume of Von Ziemssen's Handbuch der Allgemeinen Therapie. The English reader will find the subject treated at sufficient length in Ringer's Handbook of Therapeutics.

According to Ringer, the sitz-bath, taken at a temperature between 60° and 80° F., is very useful to soothe "an irritable restless state of the nervous system." It should be employed once or twice a day, from five to thirty minutes at a time. Among other beneficial consequences is the promotion of quiet sleep.

For the relief of the pungent heat and restlessness which add so much to the danger of the specific fevers cold baths have been highly recommended. These have been employed with great energy in many of the German hospitals; and often with great benefit to the patient. The preferable method is the one advised by Von Ziemssen and Immerman. The patient is placed in a tub of water at 95° F. This is very gradually cooled down, in the course of half an hour, to 60° F. The bath should be repeated from three to five times a day, according to the temperature of the patient. By this method of treatment the patient is made more comfortable; he becomes less restless or delirious, and secures a larger amount of refreshing sleep.

The difficulty of administering such a laborious course of baths outside of a well equipped hospital renders its adoption almost impossible in private practice. Here the physician must rely upon assiduous sponging with water of an agreeable temperature. In severe cases, such as measles before the appearance of the eruption, scarlet fever during the period of heat and agitation, and typhoid fever during the corresponding stage, great benefit will be derived from the cold wet sheet. In order to humor the prejudices of the laity, this should be wrung out of warm water and applied with sufficient deliberation to insure its considerable loss of heat. A blanket should first be spread upon an empty bed; the wet sheet should be spread over the blanket. The patient must be placed naked upon the sheet, which should then be drawn around the entire body, and the blanket may be folded around the whole package. Children generally insist upon leaving their arms uncovered. This may be allowed with safety in many cases, but generally a wet napkin should cover the upper part of the chest and the neck which cannot be reached with the sheet when the arms are exposed. After remaining from half an hour to two hours in the pack, the patient becomes comparatively cool and quiet, and the eruption, if delayed, begins to appear. Sleep often occurs as an immediate consequence of the relief thus obtained.

Similar good results may be secured by the use of cold affusion in cases of high temperature and great restlessness. I well remember a little boy, about eight years old, whom I once found rolling and tossing and burning up with scarlet fever. Calling for an empty wash-tub, I had him stripped and placed upright in the tub. I then began to pour cold water over him from a large pitcher. Scarcely had the water touched his skin, before he seized the pitcher, and began to drink from it. He was permitted to completely slake his thirst, and then the affusion was resumed. After four or five gallons of water had been thus poured over him, he was wiped dry, and was returned to his bed, where he immediately turned upon his side, and fell into a peaceful sleep. A few more affusions relieved him from danger, and he made a rapid recovery. Were people less afraid of such measures, a considerable portion of the danger in fevers might be obviated. Great discretion, however, is necessary in the application of such treatment, for Ringer states that he has "seen a child, suffering from scarlet fever, killed by an over-energetic employment of cold." The temperature of the patient should be carefully noted, and its reduction below the normal standard should never be permitted.

An?sthetics.-All an?sthetics are hypnotics. In other words, they possess the power to abolish consciousness, and thus to produce a condition resembling sleep. This is effected by the direct action of the an?sthetic substance upon the cellular structure of the brain, reducing the molecular movements of the living protoplasm below the degree requisite for the excitement of consciousness. This sedative effect is preceded by a brief period of cerebral exaltation, occasioned by the disturbances caused by the first introduction of the drug into the current of the circulation.[42] It is with the subsequent hypnotic effect only that we are now concerned. Of the numerous an?sthetic substances that have been discovered, but few comparatively have been found sufficiently manageable and safe for general use. These are alcohol, paraldehyde, ether, compound spirits of ether, chloroform, chloral, butylic chloral, and amylic nitrite.

Alcohol.-The hypnotic effect of alcoholic drinks is very decided, though not speedily manifested unless the beverage be taken in considerable quantity. Distilled liquors produce the effect of alcohol in its simplest form; wines, containing various forms of ether, arouse the nervous system more thoroughly and agreeably than the pure alcoholic stimulants. Beer and porter are rendered more powerfully narcotic by the active principle of hops which they contain. The nutritive substances held in solution by these last render them peculiarly appropriate in cases that require nourishment as well as rest. The considerable quantity in which they must be taken, renders them inconvenient for use in cases of severe illness. Wines and distilled liquors are then most available.

Alcohol is principally useful as an hypnotic when wakefulness is associated with great bodily exhaustion, such as may be experienced in advanced stages of the infective fevers. In such cases the heart is weakened, the pulse is rapid and feeble, the muscular apparatus is wasted and irritable, the blood is diminished in volume and tends to accumulate in the venous channels. Under such conditions the patient is usually delirious, tossing from side to side, and quite deprived of sleep. An ounce of brandy, repeated at intervals varying according to the severity of the symptoms, and given with milk and egg, in the familiar form of eggnogg, will often quiet this harassing restlessness, and will procure refreshing sleep. The temperature of the patient will then decline; the tongue will grow moist; and the delirium will diminish or subside altogether. Sometimes, however, a contrary result is observed. Alcohol should then be administered with a sparing hand, and it will probably be necessary to resort to the bromides or other cerebral sedatives.

The great exhaustion which is manifested in delirium tremens sometimes requires the use of alcohol to support the patient, so that sleep may be procured. It is in such cases advisable to combine the administration of capsicum with that of alcohol. According to Ringer, capsicum should be given for this purpose in scruple doses, made into a bolus with honey, and repeated every three hours.

Wakefulness caused by neuralgic pains is speedily relieved by full doses of alcohol. The various species of abdominal and pelvic neuralgia may thus be temporarily suspended. In like manner the "rheumatic" pains which afflict the overworked and underfed poor may be calmed for a season sufficient to procure sleep. The obvious dangers attendant upon such medication, however, need no comment.

Old people not unfrequently suffer with a form of insomnia that is associated with feeble and painful digestion. This is probably caused by insufficient gastro-intestinal secretion. The use of wine containing a large proportion of compound ethers gives relief through the improvement in digestion consequent upon the stimulant effect of small doses of alcohol and ether. Under their influence the digestive fluids are more abundantly secreted, and all the bodily functions are quickened. Such good results, however, only follow the moderate use of the stimulant. It must never be taken in quantity sufficient to affect the intellectual functions, or to disturb any of the normal processes of life. The best results, so far as digestion is concerned, are obtained by the use of wine with the meals; but a night-cap, in the form of hot toddy, is sometimes necessary in addition. This is especially useful if there be any form of irritative cough or local excitement, such as the aged sometimes experience.

The insomnia that attends excessive fatigue may be very quickly relieved by the use of food and alcohol. For this purpose any form of alcoholic drink will be found useful. The quantity administered should only be sufficient to produce a uniform and general vascular relaxation. By this means the circulation is equalized throughout the body, and the brain passes into a state of tranquil sleep. Any excess in the use of alcohol under such conditions will be followed by headache and discomfort on awaking. In all cases the intoxicating dose of alcohol must be avoided, if its truly hypnotic effect be desired.

Paraldehyde.-This is a derivative from ethyl alcohol. It is, when pure, a colorless liquid, with an agreeable odor, somewhat like that of ether. It is soluble in the proportion of one part in eight or nine of water. It may be used internally in doses varying from forty-five to one hundred and sixty grains. A watery solution, containing one part to ten, has been recommended for internal administration. It may also be given in milk or in beer. M. Yvon[43] recommends the following formula:

Paraldehyde, Gr. 20.0

Spirit, 100.0

Syr. Simpl., 75.0

Tr. Vanill?, 5.0

An ounce of this mixture contains forty-five grains of paraldehyde. When taken it should be still further diluted with sweetened water, or with beer, to obviate, as far as possible, the disagreeable taste of the drug. Sleep follows after the lapse of about half an hour, and continues from five to seven hours. The physiological action of the medicine is very similar to that of chloral hydrate, and its use is indicated in the same class of cases to which that drug is appropriate. By many it is considered the preferable hypnotic. It has found considerable employment in the insane asylums of Europe, and in other institutions where disagreeable medication is no obstacle to experiment. In private practice the peculiar taste and smell of the article, and its pungent effect upon the mucous membranes of the alimentary canal, render its exhibition more difficult. But the weight of testimony is in its favor as an hypnotic in all cases, uncomplicated with disease of the stomach, in which insomnia is not dependent upon pain, and is associated with cerebral hyper?mia. Its administration is followed by no unpleasant consequences. Among the insane it is particularly recommended during periods of excitement and wakefulness. It has been employed with great satisfaction[44] in cases of insomnia during the course of such varied diseases as emphysema, bronchitis, phthisis, nervous and spinal disorders, diseases of the heart, jaundice, chronic rheumatism, and insomnia from other unrecognized causes. Undoubtedly, with greater skill in its purification and exhibition, it will become one of the most valuable of hypnotic remedies. Almost useless for the relief of pain, it is indicated in cases of uncomplicated insomnia. Having very little power, in moderate doses, to depress the action of the heart, it is preferable to chloral hydrate in cardiac diseases and debility. Sleep procured with doses of fifteen to sixty grains is calm and refreshing, and is not followed by any disagreeable consequence. A certain degree of tolerance is gradually established, so that larger doses may become necessary. It has been given in quantities amounting to three drachms; but, if large doses be given before the development of tolerance, the patient will experience headache, uneasiness, nausea, and vomiting, after waking from the sleep thus induced. Another advantage possessed by paraldehyde consists in the absence of the period of excitement produced by chloral before the advent of sleep. It is an hypnotic, without narcotic properties, limiting its effects chiefly to the brain, and leaving the spinal cord in a condition nearly like that of natural sleep.

Ether, though possessed of the greatest value as an agent for the production of artificial an?sthesia, is rarely used as a mere hypnotic. Diluted with alcohol and ethereal oil, it forms the Compound Spirit of Ether, or Hoffmann's Anodyne. In this form it is well adapted for internal administration. It is thus very serviceable in the treatment of those forms of insomnia associated with nervous irritability and hysteria. For the relief of wakefulness dependent upon a languid circulation, with cold feet and flatulence, the anodyne may be given in half-drachm doses well diluted with ice water, and repeated every fifteen minutes till relief is obtained. Nearly all forms of painful or spasmodic disturbance unattended by fever may be thus relieved. For this reason it is particularly useful in the treatment of uterine colic and in sleeplessness after childbirth, when opiates cannot be tolerated, or are contra-indicated on account of their tendency to excite the brain.

Chloroform, like ether, is an agent too powerful and too evanescent for use as a simple hypnotic. But for the relief of intense suffering caused by nervous irritation and spasm it is without any superior. In certain minor affections of a spasmodic character it, therefore, forms a valuable adjuvant to other remedies. Diluted with alcohol it forms the spirit of chloroform, a remedy which is useful in all cases for which the compound spirit of ether is usually prescribed. In this form it is an excellent addition to various mixtures designed for the relief of spasmodic coughs by which sleep is disturbed. Ringer recommends it in the treatment of the irritative cough so characteristic of fibroid phthisis. It should also be used in cases of spasmodic asthma. The asthmatic paroxysm may frequently be arrested by inhalations of the vapor of chloroform or ether; but, unfortunately, the lungs soon become tolerant of these agents, and they then cease to afford relief. The valuable mixture known by the name chlorodyne owes a considerable portion of its efficacy to the presence of chloroform as one of its ingredients.

Chloral.-Until the recent introduction of paraldehyde, chloral hydrate has for many years held the first rank as an hypnotic. It is particularly useful in wakefulness occasioned by exhaustion of the nervous centres. The conclusions of all experienced observers have been most concisely stated as follows:[45] "Chloral appears to be indicated when sleeplessness is dependent upon a vascularity due to exhaustion rather than to primary excitement of the brain; thus it has been found useful when loss of sleep follows severe and prolonged mental application or excitement of feeling, or accompanies the general debility following acute diseases attended with delirium or severe pain, or is associated with acute mania, especially of the puerperal form. The somewhat analogous condition which exists in delirium tremens is very amenable to this medicine, especially in the forming stage of the affection known as 'the horrors,' and which so frequently follows surgical injuries in drunkards; it is useful also when great nervous excitement and restlessness are associated with extravagant phantasms. Nevertheless, its depressing effects are to be guarded against in this affection as in the different forms of insanity." This caution is directed against the frequent and repeated employment of the article in chronic cases, on account of the vasomotor paralysis and general cachexia thus induced. It is now claimed that many of these consequences may be avoided by the substitution of paraldehyde in the place of chloral, but it has been shown[46] that similar effects may follow the long continued use of this substitute.

Chloral is usually administered by the mouth in doses, for adults, of twenty to thirty grains, dissolved in sweetened peppermint water. If the first dose does not procure sleep, it may be followed at the expiration of an hour by a second dose of twenty grains. This seldom fails to induce refreshing sleep. When the medicine cannot be tolerated by the stomach it may be given by enema in milk. For this purpose a drachm of chloral should be suspended with the white of an egg in half a teacupful of milk.

Butylchloral hydrate.-This substance has been recommended as a substitute for chloral hydrate, in cases of cardiac weakness, on account of its being less powerful to depress the action of the heart. It is principally useful for the relief of facial neuralgia and hemicrania. As an hypnotic it is seldom used. For this purpose it may be given in a solution like that of chloral hydrate. For a simple anodyne effect the medicine may be given in five-grain doses, repeated every half hour or hour. As a means of procuring sleep it may be given in doses ranging from fifteen to forty-five grains. Liebreich has given the medicine in drachm doses, and recommended it as an hypnotic superior to chloral hydrate. It is useful in the sleeplessness of headaches, neuralgia, dysmenorrh?a, and chronic phthisis.

Amyl nitrite.-This drug has been recommended for the relief of insomnia resulting from the opium habit. Ringer considers it useful in the flushes of heat and other forms of discomfort which sometimes interfere with the sleep of women during the change of life. It should be inhaled in the form of vapor, from a handkerchief upon which five drops have been poured. The quantity will need to be gradually increased, as the system becomes tolerant of its effects. The stimulant effect of the medicine renders its use in this manner probably less dangerous than the similar employment of chloroform. Unlike the other an?sthetics above mentioned, it causes a hyper?mic condition of the brain, and is, for this reason, a useful hypnotic in cases of aortic obstruction with an insufficient cerebral circulation and consequent wakefulness.

Opium and opiates.-There seems to be no agreement among experimental physiologists regarding the manner in which opium produces its effects upon the body. By some it is ranked as a stimulant; by others it is considered a sedative. These different opinions are probably due on the one hand to differences in the dose and strength of the opiates employed, and on the other to idiosyncrasies on the part of the individuals subjected to experiment. The soporific effect of the drug appears to result from its direct action upon the substance of the brain. Under its influence the blood tends to accumulate in the veins, and loses its bright arterial hue. Small doses are said to contract the capillaries of the body, while they are dilated by excessive doses of the drug. From this it may be inferred that opium acts, like many other narcotics, as an irritant of the tissues when given in minute quantity, and as a paralyzing agent when a certain relative amount is exceeded. The experiments of Curci[47] indicate that under the influence of irritating doses of morphia the brain becomes hyper?mic.

Opium is a remarkably complex substance, no less than nineteen different alkaloids having been separated from it. Of these, however, only one has stood the test of therapeutical experiment-morphia. Several other constituent alkaloids, notably codeia, have been lauded as hypnotics, but they are, at their best, far inferior to morphia, and may well be omitted from the list of sleep producers. But, though the soporific properties of opium are chiefly due to the morphia which it contains, there are certain points of difference between the action of the two medicines that often render a choice desirable. According to Stillé and Maisch,[48] morphia does not stimulate circulation and the nervous system as much as opium, and its narcotic effects are less decided and speedy, though its after effects are more enduring. Opium increases the bodily temperature and sense of heat; morphia produces the last effect, but diminishes the temperature. Opium at first increases the frequency of the pulse, while morphia diminishes it. Opium is of the two the less liable to excite nausea and vomiting; hence the superiority of the tinctures and aqueous solutions of opium when nausea is specially feared.

Of all the remedies for the relief of pain opiates are the most effectual. Before the introduction of the alcoholic hypnotics and the bromides, they constituted the principal agents in the treatment of insomnia. Even at the present time they are indispensable for the relief of all forms of sleeplessness dependent upon pain. A combination of chloral hydrate, sodium bromide, and morphine forms one of the most generally useful hypnotic compounds ever employed.

Under ordinary circumstances morphia is the preferable opiate for the relief of insomnia. The sulphate is most frequently employed, but the acetate and the tartrate have been recommended on account of their supposed superiority in the formation of solutions that are unirritating and permanent in their character. The hypodermic method of administration forms the most prompt and efficient mode of procuring the effect of the medicine. It should be given in a dose of quarter of a grain about an hour before the time when sleep is desired. For some patients a longer time is necessary to develop its hypnotic effect. To children the hypnotic dose must sometimes be given at three o'clock in the afternoon in order to induce sleep at nine o'clock in the evening. As the effect of opiates is highly stimulant to the sweat-glands, and is often productive of nausea, it is advisable to associate atropine with morphine when thus given. For an adult the hundredth of a grain of atropine may be given with every quarter of a grain of morphine. The soothing and agreeable effects of morphia are thus intensified, while its disagreeable tendencies are reduced to a minimum. The injection should be made into the loose areolar tissue between the skin and the muscles. Its location is a matter of little importance so far as the relief of pain is concerned; but the neighborhood of the blood vessels should be avoided, since alarming symptoms have been observed after injection into a vein. The outer aspect of the arm near the insertion of the deltoid muscle is a favorite site for puncture. If, for any reason, the hypodermic use of morphia cannot be employed, it may be introduced into the rectum either in solution or in a suppository. The bowel should first be washed out with an enema of warm water; the opiate may then be introduced. The dose thus exhibited need scarcely exceed that usually given by the mouth; but, if the rectum is not previously cleansed, a double, or even triple, dose may be required.

As an hypnotic morphia is chiefly useful in phthisis, in cardiac dyspn?a, in diseases of the stomach which cause insomnia, in fevers with prostration and delirium, in delirium tremens, in mania, and in the majority of painful or spasmodic diseases. If the patient be violently excited, the opiate should be combined with small doses of tartar emetic, ipecac, or tincture of aconite. But in the chronic diseases it is desirable to avoid its continuous administration, not only on account of the risk of creating the opium habit, but also by reason of the injurious effects of the drug upon digestion and nutrition.

Codeine is a mild hypnotic which may be used in doses about twice as large as those of morphine. It is expensive and not very efficient, but may be sometimes prescribed with advantage when moral considerations render the use of ordinary opiates inexpedient.

Lactucarium may be classed with the weaker opiates. It possesses very little value. Its fluid extract is sometimes prescribed at night to allay the cough of pulmonary consumption, so as to favor sleep.

Bromides.-According to Mitchell, Echeverria, and Bartholow, the soporific energy of the bromides may be ranked as follows: Lithium bromide first, sodium bromide second, potassium bromide third. Hammond praises calcium bromide. Hydrobromic acid is also employed as an hypnotic in certain cases. As a clinical fact the bromides of sodium and potassium are most frequently employed for the relief of insomnia. Of these the second is most useful when sleeplessness is associated with the phenomena of irritability; the first is less energetic in its effects upon the motor structures of the body.

The bromides act upon the protoplasmic constituents of the body, directly inhibiting their functional energy. Upon the spinal cord they act to diminish reflex excitability. Under their influence the receptivity and functional capacity of the brain is reduced. The minute blood vessels contract in consequence of the inactivity of the tissues which they supply. A lethargic sleep is thus induced.

For the reasons above stated the bromides find their greatest opportunity for usefulness in cases of over-excitement and exhaustion of the brain. When the cortical cells have degenerated into a condition of irritable weakness, characterized by inordinate instability of substance, the bromides serve to steady the fabric by retarding those movements of disintegration which produce morbid wakefulness. Almost useless in cases marked by active congestion of the brain, they are invaluable in the insomnia produced by excessive mental exertion, care, emotion, worry and fatigue. The wakefulness of hysteria, of asthenic mania, and of sexual excitement, is often greatly relieved by the administration of the bromides. The prodromic stage of delirium tremens, before any violent outbreak, and the wakefulness of convalescence from acute diseases are often cured by their use. Mental disturbances and morbid impulses associated with pregnancy or the puerperal state may be dispelled in the same way. The screaming fits of night terrors in children are benefitted by these medicines. They seem to increase the efficacy of chloral, chloroform, ether, cannabis indica, hyoscyamus, belladonna, and the opiates.

The hypnotic dose of hydrobromic acid is twenty-five grains, largely diluted with sweetened water. For this reason, and for its disagreeable taste, it is not an eligible preparation. Lithium and calcium bromides may be given in scruple doses every hour or two till sleep is produced. Sodium and potassium bromides should be given in doses of thirty or forty grains every two hours.

It is sometimes remarked that instead of favoring sleep the bromides only increase wakefulness. In such cases opiates and alcoholic stimulants are usually indicated.

Hops.-The principal sedative constituent of this plant is the yellow glandular powder found in the strobiles; this is called lupulin. Hops do not exhibit any directly narcotic property; but they serve to allay nervous excitement, and thus favor the occurrence of sleep. They are principally useful in cases of irritability of the bladder and sexual organs; in dyspepsia caused by irritable weakness of the stomach; and in the exhaustion of delirium tremens. The infusion is the best preparation for internal use. It may be taken in doses of one or two ounces, as required. Lupulin may be given in doses of ten grains or more. Its fluid extract is prescribed, fifteen or twenty minims in sweetened water whenever needed. The best method, however, of securing the beneficial effects of the medicine consists in the administration of a mild beer that is rich in hops. A glass at bedtime often forms a sufficient hypnotic.

Gelsemium is a very powerful agent for depressing the pulse and the functional activity of the spinal cord. It thus favors the induction of sleep in cases attended with violent excitement, such as may be witnessed in acute mania. It has been employed in the treatment of delirium tremens; but the poisonous qualities of the plant render its use somewhat dangerous. The toxic effects are sometimes developed quite suddenly, and in a manner very alarming to the laity. For these reasons it is not to be recommended as a soporific, unless the patient can be continually under the eye of the physician or of an intelligent nurse.

Conium has been found useful in the insomnia of mania, not through any narcotic property of its own, but by reason of its sedative effects upon the spinal cord and nerves. Under its influence the excitement of the patient is so far reduced that other hypnotic remedies can produce their effect. For this purpose Squibb's fluid extract, in doses of about one-third of a drachm, or one-sixtieth of a grain of coniine, may be given sufficiently often to repress excitement. The alkaloid may be given hypodermically, and in gradually increasing doses. With it should be associated other remedies, like hyoscyamus and chloral hydrate, in order to procure sleep.[49]

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