The most interesting question regarding sleep concerns the condition of the mind during repose. We know that while the body is awake the mind is always active: does this activity entirely cease during the period of sleep? The phenomena of certain varieties of trance indicate that the mere semblance of death is not incompatible with great mental activity. In like manner, the phenomena of dreams serve to prove that various intellectual processes, such as memory, imagination, attention, emotion, and even volition, may still be exercised while every external avenue of special sense is closed by sleep. The result of the exercise of mental activity under such conditions constitutes a dream. The fact that observers who have made trial in their own persons have always found themselves engaged with the details of a dream when suddenly awakened from deep sleep has been supposed to afford valuable proof of the proposition that the mind is never wholly inactive during the deepest sleep. To say nothing of the significance of certain somnambulic states (double consciousness), in which intelligence evidently exists for a long period of time without leaving any subsequent trace in memory, the mere fact that we remember very few of the events that occupy the mind in dreams cannot be urged against the doctrine of continuous mental action, for we remember very few of the images and ideas that have stirred the depths of consciousness during the waking state. Our recollection of dreams is exceedingly variable. Sometimes we retain in memory all the events of a long and complicated vision, but usually, though entranced by the vividbeauty of the spectacle that unrolls its splendor before the eye of the mind in sleep, and though the intensity of its seeming action may be sufficient to awaken the dreamer, who recalls each incident as he reviews the picture during the first waking moments, the impression soon fades, and the coming day finds him incapable of reproducing a single scene from the nocturnal drama.
The space allotted to this article will not admit a full discussion of the physiology of dreams. A brief reference to the definition of sleep must suffice to indicate what is signified by the process. Sleep does not wholly arrest the functions of the brain. A certain amount of projection into the field of consciousness seems to continue even during the most perfect repose, and the ideas thus aroused form the material of our dreams. Our waking hours are occupied with the ideas and with the associated trains of thought that are presented in consciousness through the action of our several senses. As a consequence of the harmonious function of these senses, correcting and supplementing each other, a continuous process of logical thought is maintained. But along with the procession of ideas which are distinctly conceived by the mind, the field of consciousness is also invaded by a cloud of half-formed perceptions that are too imperfect and too fleeting to occupy the attention. As in the act of sight, though the periphery of the visual field is clouded with a whole world of objects dimly perceived without arresting particular attention, the centre of that field alone presents a clear image before the brain, so the eye of the mind perceives clearly only a few of the impressions which enter the sphere of consciousness. These neglected perceptions, however, are none the less the result of abiding impressions graven in the substance of the brain, from which, through the action of memory, they may at any favorable opportunity re-enter consciousness. It is well known that a suspension of the functions of any portion of the nervous apparatus tends to increase the energy of the remaining organs; consequently, it becomes highly probable that with the arrest of external perception in sleep the activity of certain portions of the brain must be considerably exalted, so that the impressions which they have previously registered may now more clearly reach the seat of consciousness. The probability of this hypothesis is greatly strengthened by numerous facts that lie open to observation. During the first moments that succeed the closing of the eyes mental activity and the power of attention are not diminished, but are rather increased. As the controlling influence of the cerebrum is withdrawn the reflex energy of the spinal cord becomes temporarily exalted. Witness the paroxysms of cough that sometimes harass a sleeping child who has scarcely coughed at all during his waking hours. Witness the voiding of urine in the bed by nervous children during the early hours of sleep. Witness the phenomena of night-terrors, which always occur at the time of night when sleep should be most tranquil.
It appears, therefore, that the harmonious activity of all parts of the nervous system is indispensable to the highest exercise of the conscious mind. Healthy intellectual life is the perfectly-balanced outcome of the complex polygon of forces which has its seat within the brain. But the suppression of certain lines of this polygon does not suppress life, nor does it necessarily destroy consciousness. It only occasions a redistribution of force and a proportionate narrowing of the stream of relatedideas. Since the suppression just mentioned is not an absolute quantity, but a variable factor, the polygon of forces in the brain and the corresponding succession of ideas in consciousness must necessarily be in a state of continual change. Accordingly, our dreams are as variable as the clouds that drift upon the currents of the air. As on a hot day in summer, when the steady equatorial draught has ceased to guide the wind, we may observe all manner of local tides in the masses of vapor which arise from the earth, so in sleep, when the guiding influence of the senses is withdrawn from the brain, the ideas that still arise are chiefly dependent upon its automatic and reflex action for their origin and association. Undisturbed by impulses from the external world, the brain seems then more sensitive to impressions that originate within the body. An overloaded stomach, an enfeebled heart, a turgid sexual apparatus, or an irritable nervous ganglion may become the source of irregular and uncompensated movements which may invade the cerebral cortex, and may there set in motion a whole battery of mechanisms whose influence upon consciousness would be quite unnoticed were the external senses in full operation.
The preceding argument will render it easy to comprehend the phenomena of night-terrors. These are commonly observed in young children of a highly nervous temperament before the conclusion of their second dentition. The subjects of the disorder are generally of neurotic descent. Insanity, hysteria, neurasthenia, epilepsy, chorea, and nervous dyspepsia are often discovered among their near relatives. Not infrequently they have been or will become themselves choreic.
The attack is often preceded by symptoms of indigestion, but it may result simply from the commotion of a brain wearied by the excitement and effort of the previous day. The little patient starts up out of an apparently sound sleep crying with alarm, calling for his mother, and staring wildly with every possible expression of terror. Sometimes he springs from his couch and runs headlong into a corner or seeks to hide under the bed, as if escaping from some frightful object. The eyes are open, tears flow, perspiration covers the skin, there is the greatest excitement, and the little one, convulsively clinging to its parent, will not be quieted. Only after fifteen or twenty minutes, as tranquillity gradually returns, does the child seem to recover the power of recognizing his friends. Presently, however, he lies down and falls quickly asleep, waking in the morning without the slightest recollection of the unpleasant event.
Such paroxysms occur during the early part of the night, one or two hours after the child has been put to bed, just at the time when, according to the previously-quoted experiments of Kohlschütter, sleep is passing from its maximum intensity to a lesser degree of depth. This, then, is the time when the controlling power of the sensory apparatus over other portions of the nervous system has already reached its minimum. The spinal centres and those intracranial ganglia which do not share in the full measure of this repose are therefore in a condition of relativeexaltation. Disturbances of internal organs consequently produce inordinate excitement of these waking portions of the nervous apparatus. The morbid quality of this excitement is attested both by the history of the patient and by the fact that it does not arouse the whole brain. The distribution of motion in the cerebrum is impeded, so that certain portions of the organ remain asleep while other regions are thrown into a state of tumultuous uproar. Disconnection of these different organs of the nervous system, by withdrawing particular portions from the inhibitory influence of the remaining parts, gives opportunity for violent explosions of nervous force analogous to the convulsions of a headless fowl or to the course of an epileptic paroxysm. Now, in sleep, in somnambulism, in hypnotism, in delirium, in certain stages of intoxication with alcohol or with narcotics, such ungearing of the different nervous ganglia is more or less completely effected. In narcotic and anæsthetic sleep besides the disassociation of ganglia there is paresis of the nervous molecules; hence the phenomena soon merge into insensibility and coma. But in natural sleep, in somnambulism, or in hypnotism there is no toxic paresis; hence the dissociated portions of the brain and nervous system, if aroused, are in a physiological condition to dispense great stores of force. Hence the vividness of certain dreams and the astonishing vigor of particular nervous functions in somnambulism and hypnotism.
The phenomena of night-terrors constitute merely a special form of somnambulism, a condition of which the mechanism, so far as the present state of cerebral physiology will permit, has been already suggested. The affection should not be ranked by itself as a particular variety of disease, but should rather be considered a violent perturbation in the cerebral organs of a neurotic subject during the period of sleep. In ordinary dreaming the muscular apparatus usually remains passive, even though the dream be a nightmare or an incubus of the most terrifying character. But when the desires and the emotions are powerfully addressed by the dream, a certain amount of muscular movement may ensue, as when a dog barks in his sleep, or when a child laughs upon his nurse's lap, or when a weary soldier marches on though overpowered by sleep. One night, when parched with thirst during a voyage at sea,9I saw in sleep a sparkling fountain, by the side of which appeared a young girl holding out a cup of cold water. Awakened by the excitement, I found myself sitting up in bed with my right arm extended in the direction of the tantalizing vision: my dream had merged itself in action. In like manner, the victim of night-terrors not only moves his body, but gives vocal expression of his feeling of apprehension and alarm. In like manner, projecting his dream into action, a sleep-walker may arise from his bed; he climbs out of the window and descends to the ground, executing all manner of complicated and dangerous movements; he walks long distances, and finally returns to his couch without waking. In the morning no recollection of the event of the night survives. Again, the movementmay be less locomotive in its character. The intellectual faculties chiefly may be aroused, and then only such movements are executed as may be necessary to give expression to the mental process.
9A proclivity to dreaming has often been remarked among the consequences of partial starvation.
Such, then, are the principal characteristics of somnambulism, a state in which dreams are supplemented by more or less complete and appropriate action, ordinarily without subsequent recollection of either dream or action.
The somnambulistic dream generally occurs during or soon after the period of deepest sleep, when the influences of the external world are largely suppressed. Released from the control of its sensory portion, the remainder of the brain awakes and becomes aroused to a condition of functional exaltation. No longer distracted by the recollection of the special senses, the attention is concentrated upon the hallucinations which constitute the dream. In the simpler forms of noctambulism only the automatic locomotive apparatus is awakened, and the sleeper moves in accordance with the impressions derived from habit aided by exaltation of the muscular sense. But in some of the more complicated cases a certain amount of special sensibility seems to exist. The patient is capable of exercising just that amount of sensation which is necessary to accomplish his purpose, though blind and deaf and insensible to every other impression. The more complete the waking of the organs of sense, the closer the resemblance to the condition of ecstasy in which cerebral exaltation is the prominent feature. Accordingly, it sometimes happens that the somnambulist can recall the events of his paroxysm.10In such cases the power of recollection is due to the same conditions that control the recollection of our ordinary dreams. We remember very imperfectly, if at all, the dreams that occur during sound sleep, but the visions with which sleep sometimes commences (hypnagogic hallucinations) and those that occupy the period of morning slumber are very easily reviewed in memory, because they are associated with impressions directly derived from the partially-waking organs of sense. Such dreams are therefore chiefly recalled through their association with the train of our waking thoughts. But the dreams of somnambulism and the dreams of night-terrors, and all other visions during profound sleep, are as completely as possible cut off from all connection with the mental activities which arise directly from the action of the senses. By reason of such isolation the ordinary association of ideas affords no help to the memory, and the dream remains in the limbo of oblivion.
10A. Bertrand,Traité du Somnambulisme, p. 80.
Alfred Maury expresses the opinion11that the principal cause of forgetfulness of the events of somnambulism consists in the exhaustion of the cerebral elements through the intensity of the excitement to which they are subjected during the paroxysm. Doubtless this in certain cases may contribute to the loss of memory, but it should be remembered that the excitement may be relative rather than absolute. Certain elements wake while others are asleep, and the waking cells may be aroused to a degree far in excess of what is usual during the sleep of the brain without attaining to the level of their diurnal activity. The mind, undisturbed by external impressions, gives its attention to the activity of these waking organs, and a dream with all its consequences, somnambulic or otherwise, is the result. In other words, the plane of consciousness, so to speak, is loweredduring sleep to the level of these molecular vibrations. But when the whole brain is again awakened after sleep the residual vibrations of those elements which yielded the physical basis of the dream, and which, had they occurred during the waking state, might have persisted with energy sufficient to furnish a groundwork for recollection of the ideas which they had originally suggested, are no longer sufficiently energetic to be felt in consciousness. Recollection of mental states thus generated must necessarily be impossible so long as the mind is dependent upon the brain as its register of events. Sometimes, however, the somnambulist, who while awake had forgotten all the incidents of his somnambulic experience, can remember in a subsequent paroxysm all that occurred during the preceding attack. Facts of this kind have been observed in the waking life of certain hysterical persons,12but the apparent interruptions of their personality attach to the waking state, while in ordinary somnambulism it is only in sleep that the alternations of memory and forgetfulness occur. A similar recollection of previous visions is sometimes experienced in dreams, showing the close relation that subsists between the dreams of sleep and of somnambulism. The bond of association between these events thus isolated in time must be sought in a renewal of like conditions of the brain during the successive periods of somnambulic exaltation. We must suppose that the molecules which were in a state of functional excitement during the first paroxysm are again aroused in like manner after a period of waking quiescence. If, during sleep, their movements, though of an exalted character, have only just sufficed to arouse consciousness in the form of a dream, it would not be probable that during the phase of comparative inactivity which supervenes when the whole brain is awake their residual motion could disturb the sphere of consciousness. Hence the time occupied by their somnambulic vigor must remain a blank in memory during the waking state. But when the original state of exaltation has been reproduced by a second period of disorder, if the same molecular movements be in any way renewed, the conditions of memory are fulfilled; consciousness is once more aroused as before, and the patient remembers the dream or the events of the previous attack.
11Le Sommeil et les Rêves, p. 226.
12Annales Medico-psychologiques, 5e Série, t. xvi. p. 5, 1876.
The phenomena which have now been passed in review are of apparently spontaneous origin during the ordinary period of sleep. But from the remotest antiquity it has been known that certain persons may be thrown into an artificial sleep which closely resembles the condition of the somnambulist. During the persistence of this state certain portions of the nervous system become utterly insensible to external impressions, while other portions acquire an exalted degree of sensibility. The subject of the experiment can then by special methods be placed in such relations with other waking individuals that his surviving sensations, mental processes, and physical actions shall be no longer regulated by his own volition, but by the will of another. Such susceptibility is not common to all persons. About 20 per cent. of the ordinary population is, by some observers, considered capable of experiencing this condition.Heidenhain,13experimenting upon a class of medical students, found only one in twelve who was thus susceptible. Charcot, whose field of observation covers the inmates of the Salpêtrière Hospital, finds the best exemplars of the hypnotic state among the hystero-epileptic females in that asylum. To these experimenters we are largely indebted for the most extended scientific observation of the phenomena of hypnotism, giving precision and publicity to the knowledge of facts which, though equally well known within a narrow circle of investigation14during the earlier decades of the present century, have been compelled to await the development of cerebral physiology before their full significance could become apparent to the mass of the medical profession.
13Animal Magnetism: Physiological Observations, by Rudolph Heidenhain.
14Braid,Neuro-hypnology considered in Relation with Animal Magnetism, London, 1843.
The antecedent condition most favorable to the production of the hypnotic state is a highly unstable constitution of the nervous system. For this reason the larger number of qualified subjects is furnished by the female sex, especially by those who possess the hysterical temperament. Frequent repetition of hypnotic exercises renders the subject still more susceptible. Heidenhain was at first inclined to believe that such experiences were not prejudicial to the health of the subject, but the observation of Harting in the University of Utrecht, and of Milne-Edwards in Paris,15have demonstrated danger to the health of animals subjected to similar experiments. It is easy to discover, in the various clinical narratives published by Charcot and his pupils,16evidence that hysterical patients often manifest considerable exhaustion after hypnotic exhibitions; consequently, it cannot be admitted that the practice is devoid of risk to the health of the individual.
15Lancet, July 29, 1882, p. 164.
16Paul Richer,L'hystéro-Epilepsie, Paris, 1881;Le Progrès médical, 1881-82.
Numerous methods of inducing the hypnotic state have been employed by different experimenters. The greater number consist in modifications of the sensory impulses derived from the periphery of the body. Gentle pressure upon the closed eyelids; convergence of the axes of the eyeballs upon some object nearer than the proper focal distance of the eyes; fatigue of the retina by gazing upon any brilliant or luminous object; monotonous excitation or sudden surprise of the auditory nerve; various impressions through gentle friction or pressure upon different regions of the body,—all these are capable of inducing hypnotic sleep. An appeal to the imagination, or even the mere attempt to abnegate the possibility of vigorous thought by confining the attention to the most trivial of things, sometimes suffices to produce the desired phenomenon. Thus, Heidenhain put one of his students to sleep at a distance by merely informing him beforehand that at a certain hour he would hypnotize him in his absence. The state of ecstatic meditation into which the monks of Mount Athos plunged themselves by the practice of omphaloscopy affords an illustration of the hypnotic effects of concentrated attention.
The duration of hypnotic sleep is exceedingly variable, but if left to himself the patient usually wakes spontaneously, without recollection of anything that has happened. If it be desirable to awaken him before the natural termination of the paroxysm, consciousness can be restored by almost any sudden and energetic appeal to the senses, such as anelectric shock, a sudden illumination of the eye with vivid light, or a sharp puff of air upon the face.
According to Charcot,17three principal types may be remarked among the hysterical subjects upon whom he experimented: (1) the cataleptic, (2) the lethargic, and (3) the somnambulic. Of these, the first may be developed primarily by any abrupt and powerful impression upon an organ of sense, as a bright light or a loud noise (gong). Fixing the eyes upon some object may produce the same result. Dumontpallier, for example, has reported the case of a young woman18who accidentally hypnotized herself by gazing at her own image in the mirror before which she was dressing her hair. The cataleptic state may also be secondarily induced by merely opening the eyes of a patient in whom a condition of hypnotic lethargy has been previously developed. If only one eye is thus opened, the corresponding side of the body alone becomes cataleptic. Closing the eyes causes the disappearance of this symptom, with complete restoration of the purely lethargic state. During the cataleptic condition the several tendinous reflexes disappear, neuro-muscular hyperexcitability ceases; the skin becomes insensible, but the special senses, particularly those of sight and hearing, maintain a partial activity. In this state the senses may become avenues of suggestion for the production of muscular movements, but if left to themselves the limbs remain motionless.
17Le Progrès médical, Feb. 18, 1882, p. 124.
18Ibid., March 25, 1882, p. 223.
The lethargic state may be induced by simply closing the eyes of the patient or by causing him to fix his gaze upon some definite object. The paroxysm begins with a deep inspiration causing a peculiar laryngeal sound, followed by the appearance of a little foam on the lips. The eyelids are either wholly or partially closed, and are in a state of continual tremulous motion. The eyeballs are generally turned upward and inward. The muscles are completely relaxed. The tendinous reflexes are exaggerated; pressure over a muscle or upon a nerve arouses a peculiar contraction of synergic muscles and of groups of muscles which are supplied by the excited nerve-trunk. The facial muscles, however, do not thus become contractured: they merely contract during the application of the stimulus. If the lethargic patient be rendered cataleptic by opening the eyes, these contractions persist even after awaking, and they can only be dispelled by renewing the lethargic state before resorting to pressure upon the antagonistic muscles—a process by which the contractures peculiar to this species of lethargy may always be annulled. By the approach of a magnet to a contractured limb the phenomenon may be completely transferred to the corresponding muscles upon the opposite side of the body. If upon a limb of a lethargic patient who has been rendered cataleptic by opening the eyes an Esmarch's band be applied, pressure over the bloodless muscles excites no contracture until the band is removed. A contracture is then developed, and it may even be transferred to the opposite limb by the approach of a magnet. To this phenomenon has been applied the term latent contracture.
The extraordinary muscular excitability manifested by these hysterical hypnotics is further illustrated by an observation recorded by Dumontpallier.19If one end of a caoutchouc tube one centimeter in diameter andfive or six meters in length be applied over a muscle in the leg, and if the other end be in like manner connected with a watch, every movement of the second hand will be followed by a slight contraction in the muscle. The same result follows connection with the wire of a telephone, and if a microphone be introduced into the circuit the incidence of a ray of artificial light upon the instrument, or even its glancing reflection from the eye, will arouse a responsive muscular contraction. Charcot has sometimes observed muscular contractions upon the opposite side of the body when a mild galvanic current was applied to the parietal surface of the head. During the manifestation of muscular hyperexcitability there is complete analgesia, but the senses of sight and hearing seem to preserve some degree of activity. The patient, however, does not manifest any susceptibility to influence by suggestion.
19Ibid., Jan. 14, 1882, p. 25.
The somnambulic state may be directly induced by fixed attention with the eyes, by feeble and monotonous excitation of the senses, and by various other methods of an analogous character. This forms the most common variety of the hypnotic condition. It may very easily supervene during either the lethargic or the cataleptic state as a consequence of pressure or gentle friction upon the top of the head. Thus, Heidenhain caused muscular paralysis by rubbing the scalp. Unilateral friction of the same surface produced paralysis of the opposite side of the body without notable affection of consciousness. The eye and the eyelids behave as in the lethargic state. The patient seems asleep, but there is less muscular relaxation than in hypnotic lethargy. There is no exaggeration of the tendinous reflexes, and muscular hyperexcitability is absent. But by lightly touching or breathing upon the surface of a limb its muscles may be thrown into a condition of rigidity which differs from the contracture of the lethargic state in the fact that it does not yield to excitation of the antagonistic muscles, though yielding readily to a sudden repetition of the same form of excitement by which it was originally produced. From the immobility of the cataleptic state it also differs by a greater degree of resistance to passive motion. Though analgesia may be perfectly developed in this state, there is generally an exalted condition of certain forms of cutaneous sensibility and of the muscular sense. Strange perversions of other special senses are sometimes remarked. Cohn20discovered that a patient who was naturally color-blind “when unilaterally hypnotized was able to distinguish colors which were otherwise undistinguishable.” Conversely, when the cataleptic state is induced the eye becomes incapable of discerning colors. Spasm of accommodation is also present, and is one of the earliest demonstrable symptoms of the hypnotic condition.
20Brain, vol. iii. p. 394.
These remarkable exaggerations and perversions of special sensibility have been the cause of much scepticism on the one hand regarding the verity of the phenomena of hypnotism, and of much credulity on the other, extending even to a belief in the existence of supernatural and miraculous gifts. But when the fact is once comprehended that in this capacity for uncommon feats of vision, hearing, touch, etc. we observe merely the exaggeration of a process which occurs in every act of attention, the miraculous semblance of the phenomena disappears. Attention implies an increase of activity in certain portions of the brain, withdiminution of the function in the remainder of the organ. In the wild excitement of a cavalry charge the soldier feels not the sabre cut which will fill his consciousness with pain so soon as his attention is released from the fetters imposed by the more engrossing events of the combat. So in the somnambulic sleep those parts of the brain which remain awake perform their functions with a vigor that is enhanced by a concentration of cerebral energy in certain restricted portions of an organ that, by reason of its naturally excessive instability, had been previously fitted for the liberation of an inordinate amount of molecular motion. Hence the slightest suggestion of sense may suffice for the most extraordinary perception. Such persons see through their eyelids and hear at a surprising distance. The memory of past events, the recollection of long-forgotten words and thoughts, supplies in this state an abundance of materials out of which an exalted imagination may construct the most astonishing scenes. By this method of combination are produced those remarkable oratorical utterances which by the ignorant have been so widely attributed to the supervision of guiding spirits from another world. In this condition the essential characteristics of the mind of the so-called medium become the real guides of his mental processes. Hence the infinite variety and contrariety of the utterances of such declaimers.
Among other consequences of this exalted susceptibility of the waking portions of the brain may be noticed the effect of suggestions by others upon the mind of the somnambulist. Numerous examples scattered through the literature of the subject21illustrate the manner in which the course of our ordinary dreams may be thus directed. The hypnotic dream is far more easily modified.22The simplest manifestations of such influence are exhibited in movements in obedience to the command of the hypnotizer. Next in rank are those more complicated actions that are effected by excitement of the imitative faculties of the subject. Every suggested movement that can be in any way perceived by the patient will be at once reproduced. Various emotions and passions may thus be aroused by simply placing the sleeper in the appropriately suggestive attitudes. Under the influence of a pregnant idea intruded upon the mind of the patient the subsequent association of ideas will suffice for the evolution of a complicated series of hallucinations, as in the case of a young woman, who on being directed to put out her tongue immediately began to feel sensations of uneasiness in her stomach, followed by nausea and attempts at vomiting, accompanied by the impression of being on shipboard. In the lowest grades of the hypnotic state consciousness may remain, and the subsequent recollection of the events of the paroxysm may be quite persistent. In such cases illusions that were produced by suggestions from other minds generally survive in memory and become the causes of serious delusion. Witness the manner in which susceptible individuals, partially hypnotized in a so-called spiritual circle, believe in the reality of the illusions which have occupied their senses during a séance.
21Carpenter'sPhysiology, 8th ed., p. 765;Le Sommeil et les Rêves, par L.-F. Alfred Maury, 4th ed., p. 153et seq.
22Loc. cit., p. 357.
A higher degree of insensibility to ordinary impressions is necessary to the production of the phenomena of passive obedience and of automaticimitation. It is probable that the degree of sensory hyperæsthesia which enables certain hypnotic patients to read the thoughts of others belongs rather to the first than to the last of these classes. This capacity is usually associated with preservation of consciousness and memory, and is, essentially, a mere exaggeration of that power which all possess in greater or less degree. Numerous well-authenticated examples of a surprising manifestation of this faculty have been recorded, so that the possibility of its existence no longer admits of doubt.23In all cases it has been remarked that the hypnotic mediums can only respond correctly to questions for which the true answer is present in the mind of the questioner. For all other interrogations the replies are delivered purely under the influence of random suggestion. In certain of these cases the pathway of communication lies through actual physical contact, as in ordinary mind-reading, where the insensible molecular oscillations of the muscular elements of one individual serve to guide the movements of another. But more frequently the transmission of ideas is effected through the eyes. With these organs the table-rapper or the planchette-writer reads the unspoken words of the questioner in a manner very like, yet vastly more deliberate than, that by which deaf-mutes now learn to interpret the movements of the lips of persons with whom they converse. This fact is well illustrated by the experience of Maury24in an interview with a celebrated table-rapper, who without the slightest hesitation made known to him the age, name, and date of death of a brother whom he had lost. She also gave the same information regarding his father, and related the names of other persons upon whom he had fixed his attention. But if he turned away his face or concealed his eyes, so that the woman could no longer watch their expression, her responses ceased to be of any value.
23Luther V. Bell,Two Dissertations on what are termed the Spiritual Phenomena, read at the meetings of the Association of Medical Superintendents of American Insane Hospitals at Washington and Boston in 1854 and 1855.
24Le Sommeil et les Rêves, 4th ed., p. 361.
In these partial developments of the hypnotic state it is worthy of note that the phenomena of sleep are so few and so comparatively insignificant that they are usually overlooked. Hence the veil of mystery which has so often obscured the interpretation of such cases. Careful observation, however, will always detect some characteristic departure from the normal standard—some loss of balance between the different parts of the nervous system—by means of which the true relations of each example may be determined.
TREATMENT.—A large proportion of the phenomena of somnambulism and hypnotism depend rather upon an originally irritable organization than upon a specially diseased condition of the nervous system. Their treatment, therefore, frequently resolves itself into the management of hysteria or of cerebrasthenia. But if the manifestations of somnambulism develop for the first time in a person advanced in years, who has previously enjoyed good health and a sound mind, it should be regarded as an omen of grave import, signifying the imminence of organic cerebral disease. Though the meaning of such incidents is less sinister in early life, they reveal an ill-balanced state of the nervous system and an imperfect process of nutrition in the growing body. Such children are thefrequent victims of night-terrors, the form of disorder most commonly evolved by their somnambulistic proclivities. The treatment of night-terrors should therefore be chiefly directed to the invigoration of the general health of the patient. Indigestion and malnutrition are among the most prominent antecedents, and they should constitute the principal objects of therapeutical attention. Constipation is usually present. This may be relieved by the use of compound rhubarb powder or any other gently stimulating laxative. Digestion should be aided with pepsin as soon as the catarrhal condition of the alimentary canal, so uniformly present, has been measurably improved. Cod-liver oil or its substitutes should be administered for a long period of time. If the nocturnal paroxysms be frequently renewed, it may be well to employ the bromides, either with or without chloral hydrate; but as a general rule it is better to rely upon hygienic and restorative treatment, rather than upon any form of merely hypnotic medication.
The departures from the course of natural sleep which have been thus considered are not so much the direct consequence of acute disease as the result of structural deviation from the normal type of the nervous system. We must now briefly review the strictly pathological modifications to which sleep is liable.
Among those who indulge freely in the pleasures of the table a form of insomnia is not uncommon. Originating at first in mere overloading of the stomach, and consisting in a direct irritation of the brain through the medium of the intervening nervous apparatus, sleeplessness finally becomes a symptom of more serious mischief. The tissues become charged with nitrogenous waste, and a lithæmic25or gouty condition is established. Such patients are wakeful, or if they sleep their slumbers are imperfect and unrefreshing.26Grinding of the teeth,27noticed by Graves during the sleep of the gouty, is a symptom indicative of a highly irritable condition of important ganglia at the base of the brain. These symptoms are sometimes associated with turgidity of the superficial vessels of the head, indicating imperfect function of the circulatory organs, with a tendency to accumulation of the blood in the venous channels of the body. The sleep of such partially-asphyxiated patients is fitful, irregular, and akin to stupor. Occurring in the subjects of periodical gout, these disturbances of sleep become increasingly serious as the paroxysm is approached, until loss of sleep and the unrefreshing character of suchslumber as may be obtained become important factors among the causes of failing health.
25DaCosta, “Nervous Symptoms of Lithæmia,”Am. Journ. Med. Sci., Oct., 1881.
26Dyce Duckworth, “Insomnia in Persons of Gouty Disposition,”Brain, July, 1881.
27Trousseau,Clinical Medicine, Am. ed., vol. iv. p. 362.
For all such patients a proper recognition of the cause of their disorder is essential. This must be corrected by measures appropriate to the treatment of the gouty diathesis. Since the condition of the cerebral tissues is a state of irritation caused by the presence of excrementitious substances, such hypnotic remedies must be selected as will not interfere with the defecation of those tissues. Bromide of potassium, valerian, scutellaria, hyoscyamus, hops, and cannabis indica are useful, together with all that class of drugs which quiet the brain without hindering the process of excretion. Chloral hydrate often produces an excellent result, but care should be taken to prevent its habitual use.
Closely related with the sleeplessness of lithæmia are the disturbances of repose which attend the evolution of the various specific fevers. In many cases the condition varies all the way from stupor to delirium. Excessive somnolence, such as often ushers in the fever, is an indication for evacuant treatment. Cerebral excitement calls for remedies like the bromides and chloral hydrate, which do not interfere with elimination. If pain, like headache or backache, be a symptom demanding attention, the addition of morphia in small doses forms a valuable reinforcement for the hypnotic mixture; but, as a general rule, opiates should be used with a sparing hand. The various resources of hydrotherapy are often invaluable when wakefulness results from the cutaneous irritability of the eruptive fevers. During the later stages of a protracted illness the occurrence of insomnia should direct attention to the nutrition of the patient. Wakefulness is then the symptom of an irritable weakness of the brain, demanding remedies which delay the process of disassimilation. The failing power of the heart requires attention, and diffusible nutriment must be given to convey the elements needful for restoration of the exhausted brain. These indications are most perfectly answered by the associated administration of opiates with alcohol, milk, and beef-juice in small and frequent doses.
Cerebral exhaustion is a not uncommon cause of wakefulness in cases uncomplicated with fever. It is usually the result of chronic conditions of ill-health and depression, such as are often encountered as the result of various cachexias or of dyspepsia, with or without the abuse of alcohol, tea, coffee, or tobacco. Overwork, debilitating discharges, pregnancy, parturition, mental anxiety, depressing emotions, chronic heart disease, and incipient insanity are fruitful causes of the exhaustion which produces this most distressing form of insomnia. In such cases the cessation of healthy nutrition leads to a condition of excessive instability in the cerebral tissues. The oxygen which they receive from the blood is not stored with any degree of permanence, but tends to pass directly intostable combinations with the oxidizable elements of the brain. Consciousness is thus continually aroused. The state of such a patient presents a very close analogy to the condition of the victim of diabetes whose liver refuses to retain its glycogen. The inordinate discharge of sugar into the blood not only exhausts the tissues of the liver, but also excites other organs—notably the kidneys—to excessive and unwholesome activity. In somewhat similar fashion, the failure of the brain to assimilate and to retain oxygen leads to an abnormal intramolecular oxidation, which excites an excessive and unwholesome activity on the part of the Ego in another region—namely, in the field of consciousness. Such wakefulness might justly be termed a psychical diabetes.
This variety of insomnia has frequently been ascribed to cerebral anæmia occurring as a part of a general spanæmia. But this universal impoverishment of the blood, though a sufficient cause of the morbid instability, the irritable weakness, of the cortical tissues, does not necessarily imply a comparatively bloodless condition of the brain. Unequal circulation and local hyperæmia in different organs of the body are no unusual consequences of the anæmic state. Slight disturbances suffice to arouse the brain of such a patient. The vaso-motor apparatus shares in the general irritability, permitting blood to inundate the cortical substance almost without provocation. The unstable protoplasm is only imperfectly renovated, usually at the expense of the other tissues of the body. The weary patient, busying himself with an unwilling review of the events of the day, tosses long upon his couch before he can secure the approach of “tired Nature's sweet restorer, balmy sleep.” When at length he yields, his slumbers are brief, and the latter part of the night is but a repetition of the earlier vigil.
Such patients need a very radical course of general treatment. A complete change of habits should be effected. A long vacation in the country, or, best of all, a protracted voyage in a sailing vessel, is desirable. Hot foot-baths, with cold affusion upon the head, and warm sponge-baths, or even the full bath in tepid water, at bedtime, are of great service as means of tranquillizing the nervous system. The indications for medicinal treatment, besides attention to the predisposing cachexia, are twofold—to calm and to nourish the enfeebled nervous substance. Opiates calm, but do not nourish—they hinder the process of nutrition; hence the sufferer wakes unrefreshed by the sleep which they procure, and is soon in a condition worse than ever. The same objection lies against the continuous use of the bromides. But alcohol and its hypnotic derivatives (chloral, paraldehyde, etc.) not only calm the excitable brain, but they also furnish to the tissues a certain amount of diffusible nutriment which suffices to steady the brain until a change of occupation, with rest and wholesome food, can produce a complete restoration of its normal stability. To this effect of alcohol must be ascribed its value as an hypnotic in the wakefulness of old people who cannot sleep without a preliminary nightcap. A moderate draught of hot toddy in such cases serves to arouse the feeble heart and to equalize the circulation by the production of a moderate degree of general vascular dilatation. The sugar and water afford an easily assimilated food, while the alcohol benumbs the cortical protoplasm to a degree which favors the cessation of conscious perception. If administered in excessive doses, it is not sleep but anæsthetic intoxicationwhich follows. If this condition be unduly repeated, the phenomena of chronic alcoholism supervene, with all the horrible forms of insomnia that accompany cerebral starvation and delirium tremens. Non-alcoholic nerve-stimulants and tonics, with careful administration of easily-digested food, are then more than ever needed to overcome the neurasthenic wakefulness.