Circadian Systems in Man and Their Implications

Abstract

The “biologic clock” found in all organisms accounts for such well-known phenomena in man as the variations over a 24-hour period in hormone secretion, temperature, and many other body functions, as well as jet lag. It has been found that periodic factors in the environment, like light and dark, pace the biologic rhythm but do not act as its immediate cause. Rather, the rhythm seems to be inherent in the organism.