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 somnambulic dream usually occurs during or soon after the period of deepest sleep, when the influences of the external world are most completely suppressed. Released from the control of its sensory portion, the remainder of the brain awakens, and becomes aroused to a condition of relative exaltation. No longer distracted by the solicitations of external sense, 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 actual exaltation of the muscular and tactile senses. 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 perception which is necessary to accomplish his purpose, though blind and deaf and insensible to every other impression. The more complete the waking of the sense-organs, the closer the resemblance to the condition of ordinary life, or even to the condition of ecstasy, in which cerebral exaltation is the prominent feature, and in which the power of recollection generally persists. Accordingly, it sometimes happens that the somnambulist can recall the events of his paroxysm. In such cases the power of recollection is due to the same conditions that control the recollection of our ordinary dreams. But the phenomena of ordinary somnambulism are as completely as possible removed from all connection with the mental actions which arise directly from the operation of the senses. By reason of such isolation the ordinary association of ideas affords no help to the memory, and the dream remains in oblivion. Alfred Maury expresses the opinion[90] that 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 have been 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 these 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 operation 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 lowered in sleep to the level of these molecular vibrations. But when the entire brain has been completely reawakened, the residual vibrations of those elements which yielded the physical basis of the dream, and which, had they originally occurred during the waking state, might have persisted with energy sufficient to furnish a groundwork for recollection of the ideas which they had first suggested, are no longer sufficiently forcible to be felt in consciousness. Recollection of mental states thus generated must necessarily be impossible under such conditions. 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, but the apparent doubling of their personality is connected with the waking state, or with its semblance, while in ordinary somnambulism it is only during sleep that the alternations of memory and forgetfulness occur. A similar recollection of previous visions is sometimes experienced in dreams, showing a close relationship between the dreams of sleep and of somnambulism. The bond of association between 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 excitement during the first paroxysm are again aroused in a similar 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 is scarcely 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 relative exaltation has been reproduced by a second paroxysm 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.
CHAPTER VII.
ARTIFICIAL SOMNAMBULISM OR HYPNOTISM.
| There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy. —Hamlet. |
The phenomena of somnambulism are of apparently spontaneous origin, during ordinary 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. Such a degree of susceptibility is not common to all persons. Heidenhain, experimenting upon his class of medical students, found only one in twelve who was thus susceptible. My own experiments lead me to think that American medical students are less easily influenced in this direction. Charcot, whose field of observation covers the inmates of the Salpêtrière Hospital, finds the best examples of the hypnotic state among the hystero-epileptic females in that asylum. To the experiments of Heidenhain, in Germany, of Braid, in England, and of Charcot, in France, we are indebted for the most thoroughly scientific observation and interpretation of the phenomena of hypnotism.
The antecedent physical condition most favorable to the development 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 the belief that such experiences were not prejudicial to the health of the subject, but the observations of Harting, in the University of Utrecht, and of Milne-Edwards, in Paris,[91] have demonstrated the fact of danger to the health of animals subjected to similar experiments. Hysterical patients have often exhibited considerable exhaustion after hypnotic exhibition in the hospitals of Paris (Charcot and Richer), consequently, it cannot be admitted that the practice is devoid of risk to the health of the individual.
Numerous methods of inducing the hypnotic state have been employed. The greater number consist in artificial modification of the condition of the brain through the agency of sensory impressions originated upon the periphery of the body. The simplest form of such influence is presented by the results of gentle friction of the skin with the palm of the hand or the tips of the fingers. Many an aching head has thus been relieved, many a restless sufferer soothed to sleep. In like manner, a susceptible subject may be hypnotized by any continuous and gentle excitement of the senses of sight, hearing, and touch. Concentration of the attention upon a brilliant object, like a piece of polished metal or a small mirror, especially if it be placed a little above the level of the eyes, and so near that considerable convergence of the eyeballs is necessary for distinct vision, affords a very efficient means of inducing artificial somnambulism. Certain persons may be readily hypnotized by gently pressing the eyelids together, and at the same time making slight pressure upon the eyeballs. Others pass into this condition by merely closing their eyes, and remaining motionless in a quiet room.
The phenomena of artificial somnambulism are frequently developed through the agency of impressions derived directly from the sphere of consciousness. The intellectual effort of trying to sit still and think of nothing is sometimes sufficient to induce the hypnotic state. The ordinary devices by means of which wakeful people are taught to beguile sleep, by counting, or by repeating long lists of names, etc., all belong to this category. Compulsory attention to any continuous intellectual process, like adding up a column of figures, or trying to read a dull book, is sometimes effectual. If, with these, or with similar acts of attention, be associated the expectation that something unusual is about to occur, as when the individual is aware of being the subject of an experiment, the evolution of the somnambulic condition is greatly facilitated. Thus, one of the most recent methods, consists in merely sitting, for half an hour or more, with the back towards the patient. Attention, curiosity, and expectation, are thus excited, and a susceptible person soon begins to manifest some of the numerous and various forms of the hypnotic state. Heidenhain caused one of his students thus to go to sleep in broad daylight, by simply assuring him that he should hypnotize him from a distance at a particular hour of the afternoon. The monks of Mt. Athos were accustomed to hypnotize themselves by fixing their eyes and their thoughts upon the navel; hence the reputation of omphaloscopy as an aid to ecstatic meditation.