circadian en · ADJ
Pronunciation
- /səˈkeɪ.dɪ.ən/ (UK)
- (Southern-England) audio
- /ˌsɝ.kəˈdi.ən/ (US)
- /sɚˈkæd.i.ən/ (US)
- /ˌsɝ.kəˈdaɪ.ən/ (US)
- /sɚˈkeɪ.di.ən/ (US)
Etymology
Etymology tree Proto-Indo-European *(s)ker-der. Ancient Greek κίρκος (kírkos)bor. Latin circus Latin circum Latin circā Proto-Indo-European *dyew- Proto-Indo-European *-s Proto-Indo-European *dyḗws Proto-Italic *djous Latin diēs Proto-Indo-European *-nós Proto-Italic *-nos Proto-Italic *-ānos Latin -ānus Old French -ainder. Middle English -an English -an English circadian From Latin circā (“around”) + diēs (“day”) + English -an. Compare circannual.
Meanings
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(not-comparable) Of, relating to, or showing rhythmic behaviour with a period of approximately 24 hours; especially of a biological process.
The most obvious circadian rhythm is the daily cycle of sleep and activity.
2005, Paul Martin, Counting Sheep: The Science and Pleasures of Sleep and Dreams, page 114:To summarize, the circadian system, particularly the SCN, controls the circadian pattern of melatonin release in mammals.
2002, Jill B. Becker, Behavioral Endocrinology, page 483:Circadian clocks developed early in evolution in single-celled organisms, before the animal and plant kingdom split from one another. The original clocks probably functioned to protect the cells from damage induced by high UV radiation.
2014 April 5, “Quite interesting: A quietly intriguing column from the brains behind QI, the BBC quiz show. This week; QI orchids you not”, in The Daily Telegraph (Weekend), page W22:In addition, the truck driver’s schedule involved sleeping at irregular times, including times when the body’s circadian rhythms are geared toward being awake. He was also awake at times when his circadian rhythms were geared toward being asleep. The time of the crash, about 1:36 a.m., is when sleepiness tends to be greater and performance capabilities are lower.
2024, NTSB, Highway Investigation Report, HIR-24-05:The circadian clock is involved in the regulation of the diurnal sleep-wake cycle, […].
2000, Arnold Sameroff, et al: Handbook of Developmental Psychopathology, page 310:
Coordinates
Deriveds
semicircadian · circadian dysrhythmia · circadianly · circadian rhythm · circadian clock · noncircadian
Relateds
circannual · circalunidian · circalunar · circasemidian
Synonyms
diurnal · quotidian · nychthemeral · diurnal · nyctohemeral · daily · hemeral · hemeral · quotidian · circadian · per diem
Translations (20)
de circadian (relating to rhythmic behavior with a period of 24 hours) · el κιρκάδιος (relating to rhythmic behavior with a period of 24 hours) · de zirkadian (relating to rhythmic behavior with a period of 24 hours) · pl całodobowy (relating to rhythmic behavior with a period of 24 hours) · fr circadien (relating to rhythmic behavior with a period of 24 hours) · sk denný (relating to rhythmic behavior with a period of 24 hours) · sk cirkadiálny (relating to rhythmic behavior with a period of 24 hours) · is sólarhrings- (relating to rhythmic behavior with a period of 24 hours) · ca circadiari (relating to rhythmic behavior with a period of 24 hours) · pl dwudziestoczterogodzinny (relating to rhythmic behavior with a period of 24 hours) · es circadiano (relating to rhythmic behavior with a period of 24 hours) · uk цирка́дний (relating to rhythmic behavior with a period of 24 hours) · ja 晦日 (relating to rhythmic behavior with a period of 24 hours) · gl circadiano (relating to rhythmic behavior with a period of 24 hours) · it circadiano (relating to rhythmic behavior with a period of 24 hours) · sk cirkadiánny (relating to rhythmic behavior with a period of 24 hours) · ga laethúil (relating to rhythmic behavior with a period of 24 hours) · ru циркадный (relating to rhythmic behavior with a period of 24 hours) · ru циркадианный (relating to rhythmic behavior with a period of 24 hours) · is dægur- (relating to rhythmic behavior with a period of 24 hours)