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 (sər-kā′dē-ən, -kăd′ē-, sûr′kə-dī′ən, -dē′-)
adj. Biology
Relating to or exhibiting approximately 24-hour periodicity.

[Latin circā, around; see circa + Latin diēs, day; see dyeu- in Indo-European roots.]

cir·ca′di·an·ly adv.


(Biology) 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
[C20: from Latin circa about + diēs day]


(sɜrˈkeɪ di ən, ˌsɜr kəˈdi ən)

of or pertaining to rhythmic cycles recurring at approximately 24-hour intervals: the circadian biological clock.
[1955–60; < Latin circā about + di(ēs) day + -an1]
cir•ca′di•an•ly, adv.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.circadian - of or relating to biological processes occurring at 24-hour intervals; "circadian rhythms"


[səˈkeɪdɪən] ADJcircadiano
circadian cycleciclo m circadiano


adj circadiano; — rhythm ritmo circadiano
References in periodicals archive ?
The mammalian circadian timing system consists of a master clock in the brain and subsidiary oscillators in almost every cell of the body.
The research led by the University of Colorado Boulder and the Medical Research Council's Laboratory of Molecular Biology in Cambridge, England showed that evening caffeine delayed the internal circadian clock that tells us when to get ready for sleep and when to prepare to wake up.
Circadian Rhythms: A Subject Collection From Cold Spring Harbor Perspectives in Biology
However, one potential side effect of operating on a 24/7 basis can be the disruption of circadian rhythms, which results in worker fatigue--the mental state between wake and sleep.
This year's Nobel prize was awarded to the three scientists who discovered the key genes in circadian (24-hour) body clocks.
Mariana Figuciro, director of the LRC's Light and Health program, the LRC research team investigated the connection between circadian stimulus (CS) and sleep, and depression and stress in office-based workers.
Lack of regular circadian sleep may be behind attention deficit hyperactivity disorder (ADHD), which affects around 75 per cent of children and adults, according to a new study.
BARCELONA, Spain, August 10, 2017 -- Two new studies refute the scientific belief that links aging with the loss of stem cell circadian rhythm.
Objective: The aim of this study is to investigate the effects of light and administration time of isoflurane on circadian gene expression in the brains and liver tissues of rats kept in light-dark cycle.
New information about how vision regulates circadian rhythm could be used to develop an eye drop that treats jet lag.
Continuous work in night shift and rotation shift disrupts the normal circadian rhythm and disturbances in the psycho-physiological function.
TEHRAN (FNA)- An research team discovered a protein that controls the strength of body's circadian rhythms.