circadian
adjective
cir·ca·di·an
sər-ˈkā-dē-ən 
: being, having, characterized by, or occurring in approximately 24-hour periods or cycles (as of biological activity or function)
circadian rhythms in activity
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In 1959, a scientist formed the word circadian from the Latin words circa ("about") and dies ("day"), and it caught on quickly. Most often, it's seen and heard in the term circadian rhythm, which refers to the inherent cycle of about 24 hours that appears to control various biological processes, such as sleep, wakefulness, and digestive activity. If you want to impress your friends, you can also use the term circadian dysrhythmia, a fancy synonym of jet lag.
Examples of circadian in a Sentence
Recent Examples on the Web
While some babies naturally sleep through the night early on, others can take months—if not longer—to fall into a regular circadian rhythm.
—
Lauryn Higgins, Parents, 3 Feb. 2025
Gambino says that eating on the earlier side also supports your circadian rhythm, your sleep-wake cycle that influences your physical, mental, and behavioral functions.
—Korin Miller, Outside Online, 24 Jan. 2025
Circadian Phase Alignment maps stimuli such as stress and exercise against circadian rhythm to recommend ideal times to go to bed and wake up.
—PCMAG, 24 Jan. 2025
Smart alarm clocks wake you during your lightest sleep phase, while circadian rhythm apps help optimize light exposure, caffeine, and sleep timing for a smoother adjustment.
—Maria Sokolina, Forbes, 22 Jan. 2025
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Lauryn Higgins, Parents, 3 Feb. 2025
Gambino says that eating on the earlier side also supports your circadian rhythm, your sleep-wake cycle that influences your physical, mental, and behavioral functions.
—Korin Miller, Outside Online, 24 Jan. 2025
Circadian Phase Alignment maps stimuli such as stress and exercise against circadian rhythm to recommend ideal times to go to bed and wake up.
—PCMAG, 24 Jan. 2025
Smart alarm clocks wake you during your lightest sleep phase, while circadian rhythm apps help optimize light exposure, caffeine, and sleep timing for a smoother adjustment.
—Maria Sokolina, Forbes, 22 Jan. 2025
See all Example Sentences for circadian
Dictionary Entries Near circadian
Cite this Entry
“Circadian.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/circadian. Accessed 16 Feb. 2025.
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circadian
adjective
cir·ca·di·an
(ˌ)sər-ˈkad-ē-ən, -ˈkād-; ˌsər-kə-ˈdī-ən, -ˈdē-
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