Circadian Rhythms and Sleep Regulation

This chapter aims to present circadian rhythms and their impact on sleep regulation. In chronobiology, various biological rhythms are distinguished, with the light-dark cycle influencing the internal clock, for example. Isolation experiments show that almost all physiological and psychological measurements (e.g., core body temperature, computational performance) follow a circadian rhythm. If individuals can decide on the light-dark cycle themselves, a 25-hour rhythm predominantly sets in. Various factors (e.g., light, social contacts) have been identified as so-called Zeitgeber, with numerous neurobiological components involved in the transmission of circadian information. The two-process model describes how circadian rhythms, alongside sleep homeostasis, regulate sleep.