Drowsiness is a sign that we ought to sleep, just as hunger is a sign that we ought to eat. Natural wakefulness means that we ought not to sleep. The child tries to obey the promptings of nature, but we think these promptings are wrong, if not wicked, and force him into all sorts of bad habits. Says Michelet, “No consecrated absurdity could have stood its ground if the man had not silenced the objections of the child.” We are slowly learning that there is no need or function of the body or of the mind that is exactly the same in all individuals, or that is always the same even in the same individual. But, in spite of this dawning knowledge, we still view with alarm any disregard of the rule, either in ourselves or another; so true it is, as Thomas Paine says, that “It is a faculty of the human mind to become what it contemplates.” We have looked upon ourselves as having certain, unvarying, imperative needs until we have almost become subject to them. CHAPTER III THE TIME OF SLEEP “Women, like children, require more sleep normally than men, but ‘Macfarlane states that they can better bear the loss of sleep, and most physicians will agree with him.’” H. CAMPBELL. The amount of sleep, like the amount of food, required by an individual varies greatly, depending largely upon the conditions at the time. Edison, for instance, can go days without sleep when engrossed in some invention, and he has been quoted as saying that people sleep too much, four hours daily being quite sufficient. In answer to my inquiry, Mr. Edison’s secretary wrote, “Mr. Edison directs me to write you that the statement is correct, that for thirty years he did not get four hours of sleep per day.” Evidently, experience taught him that an average of four hours per day, if taken rightly and at the right time, is enough for him. He keeps a couch in his workroom so as to sleep when he is sleepy. He does not need a clock to tell him when to go to bed, any more than you need a thermometer to tell you when to pull up the blankets. Edison is not alone in his views on sleep. He made extensive experiments with the two hundred workers in his own factory which convinced him and most of them that the majority slept much too long. The hands seem to have entered willingly into the trials: perhaps their personal regard for him influenced their conclusions. Napoleon Bonaparte and Frederick of Prussia were both satisfied with four hours of sleep,[1] while Bishop Taylor was of opinion that three hours was sufficient for any man’s needs, and Richard Baxter, who wrote “The Saints’ Rest,” thought four hours the proper measure. [1] It is said, however, that in later life Napoleon carried this too far, and was sometimes stupid for lack of sleep.