Table of Contents
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,ótheir 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 manís life are no longer in stable and taken by snatches, because the watchfulness requisite in wild-life under the constant strain of the struggle for existence no longer obtains. In manís 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 manís life is passed in sleep,óit seems that this fact alone should indicate the importance of sleep-states in manís 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 goad 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.