circadian

American  

[sur-key-dee-uhn] / sɜrˈkeɪ di ən /

adjective

Physiology.

1. of or relating to a biorhythm or regular biological cycle occurring once every 24 hours, such as waking and sleeping.

   Exposure to blue light at night can disrupt your circadian rhythm, making your biological clock think it's earlier in the day rather than time for bed.

   He is doing research related to the circadian cycling of hormones.

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circadian British  

/ sɜːˈkeɪdɪən /

adjective

1. of or relating to biological processes that occur regularly at about 24-hour intervals, even in the absence of periodicity in the environment See also biological clock

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Etymology

Origin of circadian

First recorded in 1955–60; from circā “about” + Latin di(ēs) “day” + -an ( def. ); see circa ( def. )

Explanation

Something that's circadian happens on a regular, daily basis. Your body's circadian rhythm is made up of processes that occur regularly every 24 hours. You'll find the word circadian in biology class, or your anatomy and physiology textbook, because it describes a biological process in the human body, as well as in other organisms. Your cycle of sleep, for example, happens on a circadian schedule — approximately every 24 hours, you become tired enough to lie down and close your eyes, a built-in rhythm that's affected somewhat by light. Circadian comes from Latin roots, circa, "about," and diem, "day."

Example Sentences

Circadian rhythms might take a noticeable hit, with nocturnal animals mistakenly waking up and starting their day only to realize that, whoa, nighttime is already over.

From New York Times • Apr. 4, 2024

Circadian rhythms, the internal biological clocks that regulate our daily activities, are essential for maintaining health and well-being.

From Science Daily • Oct. 2, 2023

But it seems to be “a genuine phenomenon” that many people report, according to Russell Foster, head of the Sleep and Circadian Neuroscience Institute at the University of Oxford in Britain.

From Seattle Times • Jul. 3, 2023

Circadian disruption doesn't only occur in shift workers.

From Scientific American • Jun. 20, 2023

“Most anxiety and stress comes from a lack of control,” said Russell Foster, director of the Sir Jules Thorn Sleep and Circadian Neuroscience Institute at the University of Oxford.

From Washington Post

Related Words

• constantly
• day-to-day
• everyday
• often
• periodic
• regular
• regularly
• routine