Thermoregulation Is Impaired in an Environment Without Circadian Time Cues

Effective thermoregulation appears to require the precise internal synchronization of the circadian timekeeping system, which is regulated against mild environmental cold exposures throughout the 24-hour day.

Abstract

Squirrel monkeys synchronized to a 24-hour light-dark cycle show a prominent circadian rhythm in body temperature which is regulated against mild environmental cold exposures throughout the 24-hour day. However, cold exposures produce significant decreases in core body temperature when the circadian rhythms of the animal are free-running in the absence of environmental time cues. Effective thermoregulation appears to require the precise internal synchronization of the circadian timekeeping system.