Evolutionary theories often emphasize that humans have adapted to their physical environment One such theory hypothesizes that people should spontaneously follow a 24 hour cycle of sleeping and walki?

Sleep and awake cycles that can normalize over time are known as the Circadian Rhythms. Significant research evidence indicates that the human body has light receptors (exclusive and independent of the eye) which can time these schedules. Furthermore, even those have night schedules also have such rhythms which indicate to them when to wake up.