Sleep Factors

Abstract

It is well known that after you have stayed awake for a number of hours you will get tired and sleepy. You may fight the urge to close your eyes and sleep, but with time the pull toward doing so increases and the desire to release into sleep becomes overpowering. Having done allnight experiments in which it is imperative to remain not only awake but also alert, I can personally attest to the difficulty of this task between 2 a.m. and 6 a.m. It is as if something—let’s call it a chemical factor or a hormone^*—builds up and causes this effect, and the longer you stay awake the more this chemical accumulates, making the effort of staying awake more difficult. Then when one eventually does sleep, this chemical dissipates, and likewise the drive to sleep.

In endocrinology, the term “hormone” is often reserved for a substance that has been chemically identified and has met the criteria established for being a hormone. The term “chemical factor” is used for a substance that has not been chemically characterized and has not qualified as a hormone.