What is a circadian rhythm?
Quick Answer
A circadian rhythm is the roughly 24-hour internal clock that regulates sleep, hormones, body temperature and other processes in nearly all living things.
The Full Story
The word circadian comes from Latin circa diem, meaning “about a day”. In humans, the master clock is the suprachiasmatic nucleus (SCN), a tiny cluster of about 20,000 neurons in the hypothalamus. Light entering the eyes signals the SCN to reset each day, keeping the clock synchronised with the solar cycle. The SCN controls the release of melatonin (which promotes sleep) from the pineal gland, body temperature cycles and cortisol patterns. Disruptions from shift work, jet lag or excessive screen light at night are linked to sleep disorders, metabolic problems and mood changes.
Key Facts
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Suggested video title for this topic:
"Your body’s 24-hour clock — circadian rhythms explained"