Wiktionary
n. The "internal body clock" that regulates the (roughly) 24-hour cycle of biological processes in animals and plants.
WordNet
n. a daily cycle of activity observed in many living organisms
Wikipedia
A circadian rhythm is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, fungi, and cyanobacteria.
The term circadian comes from the Latin circa, meaning "around" (or "approximately"), and diēm, meaning "day". The formal study of biological temporal rhythms, such as daily, tidal, weekly, seasonal, and annual rhythms, is called chronobiology. Processes with 24-hour oscillations are more generally called diurnal rhythms; strictly speaking, they should not be called circadian rhythms unless their endogenous nature is confirmed.
Although circadian rhythms are endogenous ("built-in", self-sustained), they are adjusted (entrained) to the local environment by external cues called zeitgebers (from German, "time giver"), which include light, temperature and redox cycles.
Circadian Rhythm is a 2005 action film that portrays a young woman's journey to discover who she is and why multiple enemies want her dead. The woman, Sarah Caul, played by Rachel Miner, is thrown into an artificial ‘construct’ where she must put the pieces of her life together and confront the menace that follows her every move.
Usage examples of "circadian rhythm".
The circadian rhythm, the daily cycling of physiological function, is known to go back at least to animals as humble as mollusks.
Of course, they could establish over that period of time a circadian rhythm coincident with the Mars day of 24 hours and 37 minutes, but the slight advantage of achieving this would scarcely repay the effort.
He slept deeply again, refreshed by the timeslip in every day, a little slack in the circadian rhythm, the body's own time off.
His circadian rhythm is set for a duty shift that begins later on.
There was neither day nor night, in any natural-sense, on board ship, and the circadian rhythm never worked absolutely perfectly.
There was neither day nor night, in any natural -sense, on board ship, and the circadian rhythm never worked absolutely perfectly.
Late at night the body enters a new phase of its circadian rhythm and the mind plays strange tricks.