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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.
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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of circadian

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Robertson says light pollution is increasing, which affects human circadian rhythms, and the lives of other species.

From BBC

I’ve learned from experts over and over about how exposing yourself to natural light, even on an overcast day, either resets or talks to your circadian rhythm.

From The Wall Street Journal

The circadian rhythm plays a central role in regulating cardiovascular and metabolic function.

From Science Daily

D.V.M.; a research fellow in the division of sleep and circadian disorders at Brigham and Women's Hospital and Harvard Medical School, both in Boston.

From Science Daily

He earned his PhD in 2006 from the Graduate School of Science at Nagoya University, where he studied the circadian clock in cyanobacteria.

From Science Daily

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.