An experimental study of sleep

Front matter

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Chapter I Introductory Remarks

WRITERS on sleep complain that little attention has been paid to the subject, that it is sufficient to open a text-book on physiology to be convinced of the fact that the physiology of sleep is almost entirely neglected, inasmuch as the school-physiologist usually dismisses the subject with a few phrases, often quite general and devoid of meaning. It is quite true that while one cannot as a rule be satisfied with the imperfect state of textbook-physiology which usually lingers in the hind ranks of the battle-ground of science, still one cannot blame the text-books for avoiding such a delicate subject, the nature of which is so uncertain and so highly problematic. In addition to the uncertainty of the subject of which the more conservative of school-physiologists fight shy, there seems to be an ill defined feeling which is not without some good foundation, namely, that sleep is not entirely a physiological subject, that sleep presents some very important aspects that need be taken into consideration which the physiologist is unable to deal with by his usual methods and from his standpoint alone.

Moreover there may be another reason for the indifference of school-physiology to a subject which is otherwise of such a vital importance in the whole domain of animal life. Man is more interested in active than in passive states. It is therefore natural that the physiologist should devote his attention more to waking life than to sleeping states. Besides, physiology dealing essentially with activities and functions tends to ignore states which are usually regarded as the very acme of inactivity. With the advance however of biological, physiological and psychological sciences even states of passivity can no longer be ignored, — their conditions, causation and nature must be studied and closely investigated, especially if those states are found present throughout the ascending line of animal life. The conditions for the study of sleep become all the more favorable as we reach man. We find that sleep-states in man's life are no longer instable and taken by snatches, because the watchfulness requisite in wild-life under the constant strain of the struggle for existence no longer obtains. In man's life sleep-states become more or less organized, systematized and are no longer disturbed, — they alternate rhythmically with waking states. More than one-third of man's life is passed in sleep, — it seems that this fact alone should indicate the importance of sleep-states in man's cycle of biological and physiological processes and should arouse the interest of the scientific investigator. As a matter of fact some scientific thinkers have given the subject of sleep a good deal of their attention. Although text-book physiology passes over the subject with a few meaningless phrases, the literature of sleep is really very extensive. It may be well before we proceed with the exposition of our own observations and experiments on sleep to give first a brief review of the chief theories on sleep.

Chapter II Theories of Sleep

FROM the very earliest times man wondered about sleep and attempted some explanation of it. It was supposed that in sleep the soul wanders away from the body and leaves it in a lifeless condition. Many of the savage tribes are on that account afraid to waken people lest the soul may be frightened away and not return at all to the body. That is why even at present we often hear the saying that sleep is the companion of death. On the other hand death is often described as sleep. On the same basis dreams were explained by the primitive mind, — the soul in sleep leaves the body and wanders away; on its wanderings the soul meets with all kinds of adventures and it is such experience that gives rise to dreams. In sleep the wandering soul, not encumbered by the gross body, can visit great distances in a short time and can even communicate with heavenly powers, — with angels and gods.

The impassive soul reluctant flies, Like a vain dream, to these infernal skies. Modern spiritualists adopt this ancient belief in full or express it as "the release of human personality from the subliminal. "

The scientific theories of sleep are numerous, but they can be reduced to a few main types. This reduction will help the reader to become oriented in the vast literature that has gathered about the subject. The theories of sleep may be classified as follows:

theories, which may be sub-

I)

The Physiological divided into:

a) Mechanical and b) Chemical

Pathological

Histological

4) Psychological

5) Biological

The mechanical theories are of the circulatory variety and are usually much favored by physicians, — they attempt to explain sleep by changes in the blood circulation of the cerebrum. As far back as the eighteenth century the theory of sleep greatly in vogue among the physiologists was — congestion of the brain favored by the position of the head. This view was entertained by Haller, J. Miiller, Hartley and others. Cappie has somewhat enlarged on it, inasmuch as he ascribes sleep to the venous congestion of the brain. This congestion of blood was supposed to bring about pressure on the brain with the result of depression of all the cerebral functions. The great psychologist Hartley summarises the physiological theories of his time thus: "It appears then that during sleep the blood is accumulated in the veins and particularly in the venal sinuses which surround the brain and spinal marrow. . . . And it is agreeable to this that in most dissections after lethargies, apoplexies, etc., the venal sinuses of the brain and consequently those of the spinal marrow which communicate freely with them are particularly full. ... It follows therefore that the brain and spinal marrow will be particularly compressed during sleep, since the blood then takes up more space, is particularly accumulated within the cavities of the skull and vertebrae, and the hardness of these bones will not suffer them to yield or make more room. ... In short this compression will result in sleep." These generalizations were favored by observations on the famous case of the Parisian beggar whose injured skull gave the opportunity to observe the rise and fall of the exposed cerebrum in the waking or sleeping state. Recently Mosso claimed the same causation of sleep and on similar observations. As to the circulatory changes proper, two opposing views have been taken. Some, such as Durham, CI. Bernard, Kussmaul Howell, Lehman, de Fleury ascribe sleep to cerebral anemia. Others again, such as Brown, Czerny, Broadman maintain that sleep is due to cerebral hyperemia. Claperede in reviewing the circulatory theories of sleep quotes Richet's apt criticism: "Sleep and waking states bring about all kinds of changes in cerebral circulation depending but little on the position of the head. Birds whose hemispheres have been removed still present the same changes of sleep and waking. Biologically regarded, sleep is a far more general phenomenon than that of the presence of a brain irrigated by a blood circulation. Finally the activity of a tissue is not entirely dependent on the amount of blood circulating in it." There are however still more cogent objections to such theories of sleep, objections which clearly show the incongruence of the circulatory theories. We shall point them out further in our present study.

We may turn now to the chemical theories which are far more favored by the conservative physiologist, inasmuch as they fall in with what the physiologist regards as more scientific. With the experiments of Pettenkofer and Voit on the respiratory quotient new life was injected into sleep theories. Those two investigators have found the respiratory quotient ^ is diminished during sleep. The tissues absorb relatively more oxygen during the day than during the night. This fact of the using up and impoverishment of blood of intermolecular oxygen started new life in the theories of sleep. Pfliiger, Sommer and others attempted to work out a scientific theory of sleep based on research of the biochemistry of the cell and the intermolecular activity of the oxygen-molecule or atom. Pfliiger's authority lent vitality to this view so that even Heubel whose theory of sleep is really psychological in character tries to shelter it under Pfliiger's physiological wings. 1

With the chemical theories we pass by degrees into the pathological theories of sleep. Already in the early part of the nineteenth century Marshall Hall proposed the view that sleep was a kind of epilepsy. This view however met with little favor, because of lack of facts to support it. With the advance of chemistry and of its application to physiological research, and especially with the rise of the modern views of the role of autointoxication and toxins in diseases, the pathological theories of sleep were resuscitated under the new guise of autointoxication. Obersteiner and Preyer launched the theory that sleep was arTautointoxication of the system by toxic matters accumulating in the blood, due to the

1 We may possibly refer to Loeb's work on heliotropism and sleep of butterflies as an example of a purely bio-chemical view of sleep. See Dec. Public Univ., Chicago, V. I.

activity of the various tissues. Lactic acid was supposed to be the particular substance in question. Others such as Dubois ascribed the same state to the accumulation of carbonic acid. These were followed by a host of writers such as Binz, Errero, Bouchard, Breisacker and others. The toxic and autotoxic theories of sleep enjoy quite a wide popularity, because they fall in with the scientific notions of the age. Those theories would make of sleep a pathological state, but the facts are against such a view.

By the middle of the nineteenth century, when physiological experiments on nerve-conduction were at their height, Purkinje proposed the theory that sleep might be due to the Interruption of neural conductivity between the cortical matter and the rest of the cerebrum. This view was further developed by Mautner, Warlomont, Oppenheimer and others. As a further modification of the same theory, but based on more fundamental physiological processes may be mentioned Verworn's theory which refers sleep and waking-states to processes of assimilation and dissimilation going on in the organism. At the same time with Verworn, Van Gieson and Sidis worked out their theory of sleep, basing it on similar processes, namely on anabolism and catabolism and developing the interrelation of waking and sleeping states with the symptom complexes of nervous and mental diseases. The theory of Van Gieson and Sidis is based on the variability of different levels of neuron energy. We may dismiss this latter theory in a few words as we shall discuss it in our study. We can only say here that the theory is essentially based on the concept of neuron-energy.

This brings us close to the famous theories of retractility of neuron-elements which have been of late utilized by many writers for various purposes. The development of the histology of the nervous system and especially of neuropathology have brought new life to the solution of the problem of sleep. The biological investigations of the cell by Kolliker, Remak, Nageli, Hoffmeister, Virchow, Max Schultze, Hertwig, Fol, Van Beneden, Strassburger, Heidenhein, Boveri and many others opened up new horizons for theories of cellular activities. Naturally the sleep theories came in for their share. It was not however until the researches of Golgi and Ramon Y Cajal had laid the foundation for their famous doctrine of independence and contiguity of neural elements that the theories of sleep could seize on some tangible anatomical facts and work them for their benefit. Ramon Y Cajal was the first to advance the view that the~ neuroglia-cells by their expansions and contractions bring about dissociations and associations of the neural elements with the consequent loss or reappearance of normal waking-states. A somewhat different, but closely analogous theory was launched into the scientific world by Mathias-Duval. Instead of the retractility of neuroglia cells proposed by Cajal, Duval advanced the view that the neurons and their protoplasmic processes are endowed with contractility or retractility and that the functioning and loss of functioning of neural elements are due to contractions and expansions of the protoplasmic processes of the neurons. Demoor, Pupin, Berger and others have enlarged on this hypothesis. At first even Verworn accepted this hypothesis, although he discountenanced it afterwards. Sidis assumed provisionally the same hypothesis for abnormal dissociative manifestations, but refused to accept it as an explanation for the phenomena of sleep which do not warrant the assumption of such hypothesis.

The psychological theories of sleep date from antiquity. The popular explanation is very simple, — it is a description of the phenomena, a description which the popular mind often takes for an explanation of the phenomena in question. Sleep is an abeyance of mental life, sleep is a rest of consciousness. Modern physiologists and psychologists who maintain the psychological theory of sleep have not much improved on that statement. The only modern substitute is that of inhibition. Brown-Sequard, Wundt^ Siemens, Forel, Oscar Vogt, all in different scientific phraseology refer sleep to inhibition of cerebral activity, especially of the frontal lobes where mental activity is supposed to " reside," according to some authors. Manaceine in her work on sleep echoes this view and comes to the conclusion that "sleep is the resting state of consciousness." Surely it is an elaboration of the obvious, if one has to write a whole volume in order to arrive at such an important conclusion. The only one who really made some advance in the psychological theory of sleep was Heubel, Privatdocent at Kiev University, Russia. I can say his is an excellent piece of work based on a series of well performed experiments. Unfortunately, when I started my experiments, I was not acquainted with the work of that investigator. I have gone over in my experimental research a good deal of the same work and may say that Heubel's experiments have been fully confirmed by me. Although Heubel's theory is incomplete, there is a good deal of truth in it and his work well deserves the attention of the student of sleep. His veiw may be briefly

summarized in the following statement: Mental activity

depends on the incoming peripheral, sensory stimulations; where such peripheral sensory stimulations are absent, mental activity is in abeyance and sleep results. In other words, brain activity depends on sensory activity which in its turn depends on peripheral stimulations. Psychologically stated, consciousness is a function of sensations which in their turn are a function of external stimuli or impressions. In accordance with this view a series of experiments have been carefully carried out by Huebel. As my own experiments were carried out on somewhat similar lines I shall refer again to Huebel's work, when I give an account of my experiments, in order to test a somewhat similar theory arrived at from totally different considerations, viewing the subject of sleep not only from a physiological and psychological, but also from a biological standpoint.

An altogether different departure from the usual theories of sleep was recently taken Jxy Claperede. He points out that biologically regarded, sleep has its significance not as a passive state, but as an active instinct, like all the other instincts of animal life. To put it in his own words : "Le sommeil n'est pas un etat purement negatif, passif, il n'est pas la consequence d'un simple arret de fonctionnement: il est un fonction positive, un acte de ordre reflexe, un instinct, qui a pour but cet arret de fonctionnement; ce n'est pas parce que nous sommes intoxiques, ou epuises, que nous dormons, mais nous dormons pour ne pas l'etre." This biological view of Claperede forms one of the most valuable contributions to the theory of sleep. It throws altogether new light on the subject of sleep, and many obscure until now unexplained facts can be understood in the new light of the biological standpoint taken by Claperede. Claperede's physiological theory of inhibition is not as clear, but with some modification I think it could well harmonize with my views and my work on sleep. While accepting the views of Claperede, my standpoint taken in this study is based on investigations published in previous works of mine mainly dealing with the subject of dissociative states in general.

Chapter III The Conditions of Sleep

TAKING the well-known dictum of Newton, " Hypotheses non fingo," let us start with facts before we attempt to form any idea as to the nature and character of that apparently mysterious state known as sleep. In order to understand a highly complicated phenomenon it is well to study the circumstances under which it occurs and investigate the conditions that favor the manifestation of the state. Now in studying the conditions of normal and abnormal suggestibility, I pointed out in my "Psychology of Suggestion" that the following conditions are requisite to bring about those peculiar subconscious or subwaking states which form the soil favorable for the growth and development of implanted suggestions.

Conditions of Normal Suggestibility Abnormal Suggestibility i) Fixation of attention

2) Distraction of attention

3) Monotony

4) Limitation of voluntary

movements

5) Limitation of conscious-

ness

6) Inhibition

7) Immediate execution of

the suggestion

1) Fixation of attention

3) Monotony

4) Limitation of voluntary

movements

5) Limitation of conscious-

ness

6) Inhibition

I have further pointed out that what we really bring about under such conditions is a dissociation of consciousness. In the normal waking state the dissociation is transient, fleeting, disappearing at the very moment of its appearance, while in abnormal suggestibility the states are more or less permanent. In other words, the waking state tends to disappear under the conditions mentioned above. Now to induce sleep the first requirement is the displacement of the waking state. It is evident that the conditions that favor the suppression of the waking state would also favor sleep-states. As a matter of fact I have often observed in my patients and subjects that the conditions by which I intended to bring about a subconscious state in general and a hypnotic state in particular have often resulted in ordinary sleep. I have found quite frequently that the close observation of the conditions of monotony, limitation of the voluntary movements, limitation of the field of consciousness and of inhibition, brought about not a hypnotic state, but ordinary sleep. I began to experiment on myself and found that I could put myself almost at any time into a state of deep sleep by closing my eyes and keeping perfectly still, dismissing all ideas from my mind — closing shop, so to say. I was able to put myself into a quiet, prolonged and often very refreshing sleep. I have further succeeded in the treatment of many cases of insomnia, by following the same lines in bringing about good therapeutic results.

After many years of experimentation and observation I have come to the conclusion that this could not possibly be an accidental matter, but that there must be some close interrelation between sleep-states and the conditions of normal and abnormal suggestibility. In other words, the conviction was almost forced on my mind by the facts that the conditions I found requisite for the induction of dissociated states and for normal and abnormal suggestibility in general play also an important role in the induction of sleep.

There is one fact that is specially worth while noticing in the process of falling asleep, and that is, the circumstance that we do not tumble into it in spite of ourselves, that we go about it in a deliberate, may be cold-blooded fashion.

II

We have to make up our minds and decide whether or no we want to go to sleep, or whether it is best for us to be asleep; and when we decide in the affirmative, we undress and go to sleep. The whole affair is not the after-effect of some narcotic, toxic, autotoxic bodies, nor the result of some involuntary automatic mechanism, — it is a voluntary act, — the result of decision. In this respect sleep is very similar to the abnormal state of suggestibility in which subjects can be artificially put. The state of abnormal suggestibility, the hypnotic state, is not induced by accumulation of toxic products in the system. The state can be brought about at will under the conditions described above. It is a purely voluntary affair, requiring the cooperation of the subject's and the experimenter's attention, active and steady. In fact, subjects whose attention is poor, — imbeciles, idiots, insane persons or persons whose attention is constantly wandering and fluctuating, are extremely difficult to hypnotize. These significant facts so often overlooked by writers on the subject, force on one the conclusion that the psychic factor is of the utmost importance in the formation of sleep-states. If we now scrutinize the conditions under which drowsiness and sleep occur, we find that they differ in some very important points from those requisite in the induction of hypnotic states. In the bringing about of hypnosis the most favorable condition is the fixation of the attention on some object, perceptual or ideational.

So much is this condition of fixation of importance that some writers describe the nature of the subconscious by this one condition of the attention, and characterize the hypnotic state, not without some show of plausibility, as a cramp of the attention. Such a sweeping statement is not entirely true to fact, but it is true that fixation of the attention, steady and persistent, without flinching, constitutes a very important factor in the induction of the hypnotic state. In sleep, however, we observe that the condition is somewhat modified, — it is not fixation of the attention that is conducive to sleep; in fact, fixation of the attention is more favorable to insomnia or to the prolongation of the waking state. What is requisite is a relaxation of the attention. If fixation of the attention is present at all, it is only present in so far as it is requisite to have the attention relaxed, which under some conditions requires either an effort of the will or the presence of specially favorable circumstances. It is the will to give up all active relations, sensory and motor, with the external environment. In hypnosis there is present at first a strained state of attention; in the induction of sleep the strain is practically reduced to its minimum. In the formation of sleep-states all active desire must cease. That is why people with intense, active desires and emotions find it so difficult to fall asleep. On the other hand such intense desires and strong emotional states may, if taken advantage of at a favorable moment, become the best condition for bringing about states of suggestibility, hypnosis and all forms of dissociation. In fact, in this respect we may say that the sleep-states differ fundamentally from hypnotic states. Suggestibility, which is the characteristic trait of subconscious states and of hypnotic states in particular, is absent in sleep-states. While hypnosis and allied states are characterized by a greater facility of reactions to external stimulations, the sleep-states on the contrary are characterized by an almost complete suppression of the more complex reactions associated with mental processes. In other words, in hypnosis and allied states there is a suppression or inhibition of the inhibitions present in waking life; in sleep, on the contrary, the inhibitions are intensified. If put in terms of the threshold theory advanced in my work, "Multiple Personality," we may say that in hypnosis and allied states the thresholds are lowered, while in sleep states the thresholds are raised.

If we turn once more to the conditions of sleep, we find that limitation of the field of consciousness and limitation of voluntary movements play a very important role in the bringing about of sleep-states. In this respect Huebel's shrewd observation is correct, — the cutting off of all external stimulations tends to bring about a languid condition akin to sleep. Prisoners in solitary confinement, unless they find a source of mental activity by getting some external stimulations to awaken their mental life, have a tendency to sleepiness. Where attention is relaxed, or the interest in external impressions is gone, there drowsiness supervenes.

In the limitation of voluntary movements a mass of muscular sensations as well as kinaesthetic sensations is kept from pouring into consciousness, the result is a lowering of mental activity, a rise of thresholds characteristic of sleep. The cutting off of external impressions is also of importance in hypnosis, as when the subject is asked to keep very quiet and make his mind a "blank." Where there is a predisposition to states of dissociation the result of limitation is not sleep but hypnosis, with a fall of thresholds.

The most important and possibly fundamental condition common to sleep and subconscious states is that of monotony. In order to fall asleep we must dismiss all our interests, all our thoughts. Similarly, to induce hypnosis we tell the subject to try not to think of anything. We impoverish, we make monotonous, his mental life by making him think of "nothing in particular."

The fact that people may fall asleep even under intense stimulations is often adduced as a strong objection to the view that diminution of sensory stimulations is conducive to sleep. Thus Richet refers to the fact of "falling asleep at the opera, in spite of the light and the noise." This objection is valid only if we leave out of account the importance of the factor of monotony. It is not so much the diminution of the intensity of stimulations which is of importance in the production of sleep, as the total mass of impressions. In fact, it is not so much the total volume as the progressive, ceaseless variability of the incoming impressions that counts in the keeping up of the restless activity of consciousness in its adjustment to the external conditions of the environment. Given a prolonged stimulation or a series of stimulations of the same intensity, consciousness becomes dulled and sleep ensues. In fact, the more intense the monotonous stimulations are, the deeper is the state of sleep.

It is interesting to note that under such conditions the intensity of the series of monotonous stimulations tends to keep up the sleep-state. With the cessation of the monotonous stimulations the sleep-state tends to disappear. The miller falls asleep under the continuous uniform noise of his mill, and wakes with the cessation of the noise. In listening to lecturers in a medical school I found how easily the monotonous, uninteresting delivery put me into a drowsy state, and how I came back to myself with a start when the lecturer stopped. Inquiring among the students, I found that their experiences were quite similar to my own; they were kept in a semi-drowsy state by the long-drawn-out sentences, and kept awake by the lecturer's resting-places. Many people who are used {o the long, continuous hum of a large city such as New York, for instance, find it difficult to fall asleep in a quiet place.

Chapter IV Intermediary States

IN many cases where it is requisite to find the causation of the mental trouble, and hypnotization is not possible, I have for many years employed a method which has been giving excellent results, both theoretical and practical. By means of this method, which I have termed hypnoidization, I have been able to induce states closely allied to sleeping states on the one hand, and to hypnosis on the other. This work may be regarded as established, having since been confirmed by many other investigators, as well as by my assistants and collaborators in my laboratory.

Basing myself on the conditions which I have elsewhere described for the induction of states of normal and abnormal suggestibility, as well as for the bringing about of dissociated states in general, I have applied the same or similar conditions in cases where hypnosis was not possible. The result was the induction of peculiar states which I termed hypnoidal. The hyp/ioidal state is of an intermediary character, intermediary between the waking state on the one hand, sleep and hypnosis on the other. Here specially lies our present interest in these peculiar states. The patient or the subject while in this state hovers between hypnosis and sleep. Now he may be in a condition which can only be characterized as light hypnosis, and then again to one's surprise the person is found to be in his normal waking state. The state evidently is highly unstable.

The oscillations of the different states may be followed by variations in respiration. Thus the respiration is somewhat unequal in the waking state, becomes quietened and more uniform in hypnosis. When, again, in the hypnoidal state the respiration is slow and with little or almost no variations, it becomes disturbed when the patient passes into waking state, and becomes uniform when he passes into hvpnosis or sleep.

The method of hypnoidization shows clearly how the conditions of normal and abnormal suggestibility are utilized and modified in the induction of hypnoidal or intermediary states. I say modified, because it is just on such slight modifications and variations of the conditions mentioned above that the whole matter of hypnoidal states hinges. A quotation from a previous work of mine giving a short description of the methods of hypnoidization and of the character of the hypnoidal state will be opportune here. " The patient is asked to close his eyes and keep as quiet as possible, without however making any special effort to put himself in such a state. He is then asked to attend to some stimulus, such as reading or singing, or to the monotonous beats of a metronome. When the reading is over, the patient with his eyes shut is asked to repeat it and tell what comes into his mind during the reading, or during the repetition, or immediately after. This should be carried out in a very quiet place, and the room, if possible, should be darkened so as not to disturb the patient and thus bring him out of the state in which he has been put. As modifications of the same method, — the patient or subject is asked to fixate his attention on some object, while at the same time listening to the beats of a metronome; the patient's eyes are then closed, he is to keep very quiet, while the metronome or some other monotonous stimulus is continued. After some time, when the patient's respirations and pulse are found somewhat lowered, he is asked to concentrate his attention on a subject closely relating to the symptoms of the malady or to the submerged subconscious state. In other words, the patient is in a hypnoidal state favorable for the emergence of subconscious experiences.