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AN EXPERIMENTAL STUDY OF SLEEP
Boris Sidis, Ph.D., M.D.
Boston: R. Badger, 1909
Experiments on Cats
IN passing now to my experiments on higher animals the results seem more striking and convincing. As in the case of the frogs, I can only quote some of the experiments performed, it would take up too much space of the present paper to quote all of them. Besides little will be gained by a literal transcription of my notebook, since many of the experiments are simply repetitions of one another. I shall bring as many facts before the reader as will sufficiently introduce him to the work and make him so familiar with the experiments performed that he may be enabled to follow closely the various threads that go to form the main strength of the present research.
A young kitten of about six weeks, very lively, runs about playfully, wide awake. When put on its back, it struggled violently. I then put the kitten in a cloth, kept it firmly so as to limit all the struggles and voluntary movements. At first it struggled and fought, but I restrained the kitten as much as possible, and then I closed its eyes for about a minute. The struggles ceased gradually and the kitten passed into a passive state of sleep. When I relaxed my grip on its body, it remained in the same position without moving a limb. At first the respirations went up and also the heart-beats. But as the kitten became more passive and went into deep sleep, the respirations and heart-beat fell. The kitten was deeply asleep, did not react to sound stimuli or to light; eyelids were firmly closed. At first a slight resistance in the outstretched paws, strongly suggestive of hypnotic catalepsy, was observed, soon the paws were fully relaxed and easily changed to any position, but without retention of impressed posture. The sleep lasted for more than twenty minutes and would have lasted longer, had it not been for the fact that I disturbed the kitten’s repose to continue my experimental work.
The same experiments were repeated again and again under the same conditions of monotony, limitation of voluntary movements and inhibition. The results were uniformly the same. It may be well to call the reader’s attention to the fact that holding the kitten down firmly, thus limiting its voluntary activity, is really at the same time conducive to greater monotony of peripheral sensations coming from the action and movements of the muscles, joints, synovial surfaces and so on; so that the factor of limitation largely aids the condition of greater monotony. Although the pressure exercised on the animal during restrictions may be intense, still, as we have pointed out, it is not so much the intensity of the sensory mass which keeps up the waking state, as the manifoldness and the volume of sensations and reactions ceaselessly varying from moment to moment as to quantity, quality and intensity.
The kitten was restricted in its movements; it was held down for some time, but it did not go easily into a quiet state. I found that the best arrangement was to enwrap the extremities, the hind extremities at least, in a cloth. This limited the voluntary movements effectually. It was still easier, when all the extremities were enwrapped in a cloth. When now I put my fingers over the kitten’s eyes and closed them, there was little resistance and in a few seconds, not more than half a minute, the little thing was extremely quiet and in a minute or so it was fast asleep. The fingers were then removed, the kitten’s eyes remained firmly shut. In fact, the eyelids resisted all efforts to open them. When forcibly opened, the eyeballs were found rolled up and the pupils were contracted. The kitten would have probably kept on sleeping for some time, if judged by what had been observed in other kittens under similar conditions, had it not been disturbed in order to have the experiments repeated. The kitten was snugly put away in a cloth, and all four extremities were restricted from voluntary movements. At first the kitten struggled a little, but was soon quieted. I then shielded the kitten’s eyes with my hands, while I held it firmly for a few seconds only. The kitten's eyelids became half closed and finally closed fully. When the extremities were tested immediately, they were found resistive and slightly cataleptic. Occasionally the resistance was quite marked. The cataleptic state was rather transient. In some experiments I even succeeded in raising the paws into uncomfortable postures where they remained without change for a brief period of time. After a few seconds the catalepsy of the extremities passed off and the limbs were in a state of relaxation. The kitten did not react to stimuli, such as sound, light or smell; even slight pinching, change of the extremities, shifting of the posture of the body did not produce any reaction. When aroused from sleep, the kitten yawned and stretched its paws, looked sleepy and reacted sluggishly to external stimulations.
Kitten struggled hard when put on its back. It was enwrapped in cloth and still kept on its back, where it was held firmly without being allowed to turn over or even to move. I then closed the kitten's eyes. After a minute it remained in the same position. The kitten was lying quietly on its back, though the position was rather unusual and the whole attitude was very uncomfortable. The paws were raised in the air and at first there were manifestations of resistivity about the joints, but soon the resistivitv passed off and the limbs, though raised, were really soft and relaxed. A little later the paws dropped slowly and remained in a state of relaxation. The catalepsy was replaced by lethargy. The kitten did not react to pressure or to tickling of the paws. When sounds were produced close to its ear, the ear moved, but otherwise, the posture of the kitten remained unchanged. Tickling of nostrils made it move its head, but the kitten remained in the same posture with eyes firmly shut.
The kitten was wrapped in its cloth as usual. At first the kitten was greatly excited and squealed. It was rather more difficult to make the kitten quiet than it was in previous experiments. The excitement was antagonistic to sleep. When finally quieted, which took some time, the result was even more successful than on previous occasions. The kitten was fast asleep. Before going into the sleep-state the same phenomenon of transient catalepsy and resistance was quite marked. The limbs then assumed a relaxed condition. It slept so soundly that stimuli that would have awakened the kitten on previous occasions did not disturb it at all, but simply called forth reflex reactions. The kitten slept for more than half an hour. It was then rudely awakened by me. The kitten was very sleepy and soon closed its eyes and sank once more into a deep sleep.
Three kittens eight days old. Eyes were open. Their movements were still incoordinate. They resisted, when put upon their backs. The kittens were wrapped in a cloth one by one. At first they struggled violently, but afterwards they became quiet and fell into a deep sleep. The limbs were in a state of relaxation. No manifestation of rigidity or of catalepsy could be observed while passing into or coming out of sleep. The induction of sleep took some time, but a few repetitions made the onset of sleep easier.
The kittens were wrapped in a cloth and their movements were restricted. After a little struggle and spitting they went to sleep. This time no symptoms of catalepsy could be observed. The kittens were probably too young to manifest any of these phenomena, for later the phenomena of catalepsy during the time of going into and coming out of sleep were, relatively speaking, quite marked. Closing the eyes did not play such an important role in young kittens as did the condition of limitation of voluntary movements. In this respect young kittens behave somewhat similar to young infants.
Kitten, two and one half weeks old; very lively. It struggled to get free. After three minutes the kitten was put to sleep; it was wrapped in a cloth and slept peacefully. On my attempt to open its eyes there was a little resistance, but not marked. On examination the eyeballs were not found rolled up, but they looked staring and sleepy, and the pupils were contracted. The kitten closed its eyes immediately after and went to sleep again. There was little or no response to external stimulations of sound. In the next room much noise was made by a carpenter hammering with all his force. This was not favorable to sleep, but the kitten was deeply asleep and remained undisturbed. The kitten slept for fifteen minutes and was awakened by me for further experimentation.
The cloth has proved itself an excellent factor in putting the animals to sleep. This may be due to the fact that the movements are well limited without much pressure; the pressure present is more evenly distributed, hence, also more monotonous, a circumstance which greatly helps in bringing about sleep. The conditions must all cooperate to bring about monotony.
An attempt was made to put a kitten to sleep without the cloth. The animal was harder to handle, it took me some ten minutes before the kitten was made quiet. It fell asleep but for a brief period of time, possibly not more than a minute. Then it opened its eyes. Now for that short period the paws were found extended, somewhat resistive to but retentive of impressed movements. The paws trembled visibly. This tremor was due to the incoordination of the motor activity of the kitten.
I observed in my experiments on subjects and patients that sudden fright might bring about subwaking states and sometimes even hypnotic and somnambulistic states. Now when tested on kittens similar results were obtained. When the kitten happened to be specially refractory, it was frightened by sudden strong stimulations or by suddenly turning it around and around. To my great surprise I found that the kitten’s struggles subsided,—the respiration became lowered and the kitten was asleep. As the experiments gave like results the few described will be sufficient for our purpose.
When one of the kittens was very excited and in a fighting mood, I seized it suddenly, kept it down firmly, the animal became very quiet, fell into a passive state and then was fast asleep.
Of three young kittens I seized one after another quite suddenly. The kittens became much excited. One after another was put in a cloth, their limbs wrapped all round and kept down quite firmly, so that they could not move. There was but little opposition and still less fighting. By way of intensifying the effect they were given a couple of good shakings, the little ones became quiet, and fell into a sound sleep. They did not react to sensory stimuli; their paws were slightly resistive at first and then relaxed. Respiration, from being labored and quick, became quiet, uniform, easy and lowered.
These experiments were repeated by me over and over again and with the same results, showing that the latter were not a matter of accident. In fact I found that when I wanted to put the little kittens to sleep speedily, to frighten them by shaking was the surest way of putting them into a more agreeable mood and thus send them off without delay into a sound sleep.
In the experiments on the kittens we find the phenomena of the subwaking states somewhat more developed than in the guinea-pigs or in the frogs. The cataleptic phenomena are not so pronounced as they are in the frog, but the manifestations of the subwaking states approach more closely the manifestations observed by me in human subjects. The state is more hypnoidal in character, there is present the transient, scarcely perceptible catalepsy which appears for but a moment, giving way immediately either to sleep or to the waking state. Of course, we should not expect to meet with a typical, fully developed suggestibility or somnambulistic state in guinea-pigs or in kittens, considering the fact that even in man, the imbecile, the idiot and the mentally obtuse hardly go into any such state. It requires a mind of a highly organized constitution to get into a state of abnormal suggestibility and of somnambulism with their accompanying manifestations. What, however, we do find is the characteristic instability of the manifestations of the intermediary, subwaking, hypnoidal states, having some of the most general somatic symptoms of hypnosis, such as slight catalepsy, but leading into a passive condition on the intensification of the state. The state in which the animal is plunged under the condition of monotony and limitation is hypnoidal leading toward sleep.
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