The Phenomenon Of Sleep
( Originally Published 1936 )
Professor Laird of Colgate university has made some scientific studies of "Sleep," recently published in an interesting little book of that title.
A number of volunteers from the student body agreed to be human guinea-pigs for experimental purposes, and the professor and his associates tried out all kinds of ideas on them.
There are five general theories of exactly how and why we go to sleep. None of them are proved.
First is the blood circulation theory—that sleep is induced when the blood in the brain is reduced. But when you go on to ask why the blood in the brain is reduced, no one can answer.
Second is the theory of waste products accumulation—that bodily activity produces poisonous products and these create sleep. But in answer to that it is well known that invalids in bed, or paralyzed persons, who have little or no muscular activity, sleep very well.
Third is the nervous theory. That the tentacles of the nerve cells in the brain shrink up and lose contact with one another. But again comes the question, why?—still unanswered.
What may be called the theory of nature is that sleep is a fundamental life condition brought about by the regular recurrence of night.
The psychological theories are numerous. Freudians say sleep is a longing to return to babyhood, or even beyond, to be still and quiet in the mother's womb. Dejerine, a French neurologist, calls it "a reaction of disinterestedness." But one wonders whether he ever tried to put a little child to sleep. The child certainly still is interested, but eventually—usually, thank heaven—goes to sleep.
Professor Laird does not try to prove or disprove any of these theories, but he studied the phenomena of sleep.
He found for one thing, you go to sleep in sections—not all in one piece, as the term "falling asleep" would imply. Different parts of the body get under the influence at successive times. The muscles come first. Power of voluntary movement is first lost. The last thing to go is hearing—response to noises.
And you wake up in reverse order. Hearing returns first, and last, power of movement.