Circadian rhythm
Article
A circadian rhythm is an endogenous biological oscillation with a period of about 24 hours. Circadian rhythms are found in animals, plants, fungi, and microorganisms and help organise physiology and behaviour in relation to the day-night cycle.
Examples include sleep and wakefulness, body temperature, hormone secretion, feeding behaviour, photosynthesis, gene expression, and metabolic activity. The rhythm can persist in constant conditions, demonstrating that it is generated by an internal clock rather than being only a direct response to light.
Environmental signals synchronise or entrain the clock to local time. Light is the strongest timing cue for many organisms, while feeding, temperature, exercise, and social schedules may also shift circadian phase.
In mammals, the suprachiasmatic nucleus coordinates many rhythms, while clocks in peripheral tissues regulate local processes. Misalignment between internal timing and external schedules is associated with jet lag, shift-work effects, sleep disturbance, and changes in metabolic and psychological function.
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- Source / publisher: Wikipedia
- URL type: WWW
- Credits: Wikipedia
- URL: https://en.wikipedia.org/wiki/Circadian_rhythm