Circadian Rhythm
/sər-kā-dē-ən ˈrɪð-əm/
noun — “the body’s quiet clock that keeps insisting it knows what time it is, even when everything else disagrees.”
Circadian Rhythm is a biological timing system that regulates cycles of sleep, wakefulness, hormone release, body temperature, and a wide range of internal processes over an approximately 24-hour period. It is not a literal clock with gears, but a distributed regulatory system embedded in living organisms, tuned by both genetics and environmental signals such as light and darkness.