circadian rhythm
Pronunciation: sir-KAY-dee-an
The internal biological clock that regulates the sleep-wake cycle and other physiological processes over approximately 24-hour periods.
Full Definition
The endogenous biological timing system that orchestrates daily fluctuations in physiological and behavioral processes, including sleep-wake patterns, hormone production, body temperature, and metabolism. Controlled primarily by the suprachiasmatic nucleus in the brain's hypothalamus, circadian rhythms respond to environmental cues like light and darkness to maintain synchronization with the external world. Disruption of these rhythms through shift work, jet lag, or certain medical conditions can lead to significant sleep disorders and health problems. The timing and strength of circadian rhythms vary among individuals, influencing whether someone is naturally a morning or evening person.
Usage
Usage note: Often used with 'disruption,' 'disorder,' or 'misalignment.'
In Context
- "Shift workers often experience circadian rhythm disruption that leads to insomnia and excessive sleepiness." — Occupational health report
- "Light therapy can help realign disrupted circadian rhythms in patients with delayed sleep phase syndrome." — Treatment protocol