Scientists Say: Circadian

Circadian (adjective, “Sir-KAY-dee-in”)

A period of about 24 hours. Rhythms that vary over a 24-hour period are described as circadian. Our sleep schedules are circadian. Similar 24-hour rhythms are found in other animals as well as plants, fungi and even bacteria.

In a sentence

When we stay up late reading on a brightly lit device, the light and late hours may mess with our circadian rhythm and disrupt our sleep.

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Power Words

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circadian  Recurring naturally on a 24-hour cycle.

circadian rhythm  Biological functions such as body temperature and sleeping/waking times that operate on a roughly 24-hour cycle.