SLEEP
From observation and study of the state we call sleep, we notice that as night approaches and the activities of the day wear upon us, both the nervous and the muscular organisms relax, so that it becomes more and more difficult to maintain a positive and an active attitude of mind. There is a tendency toward cessation and rest, which gradually brings upon us that passive condition called sleep.
Evidence of acquired energy during sleep
In spite of the fatigue often experienced before we retire, we awake again on the morrow with renewed strength and power. From these and other reasons we are led to believe that during the hours of activity the body is constantly expending vital energy in both internal and external work, and that during the hours of sleep, through some unknown process, the body is charged with vital energy which is stored up and used gradually for carrying on the various functions and activities of the system.
The mystery of energy
Just what this energy is, just where it comes from, just how it is stored, just the manner in which it is delegated to the body, we cannot say. We can only observe its workings, or effects, and formulate therefrom a theory. We are led to believe, however, that this energy is stored in the nervous organism, perhaps most largely in the brain, as brain tissue is the last to break down or waste away in sickness, ill health, dis-ease, or starvation, often maintaining its full weight up to the point of death.
Vital processes expend energy during sleep
Even in sleep the expenditure of energy in the vital processes continues vigorously, depending upon conditions immediately preceding sleep, but usually in a much more passive degree than in the waking hours. These activities, however, are no more pronounced in their constructive action or repair, than in ordinary periods of rest during the waking hours.