circadian rhythm

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Related to Circadian rhythms: biological clock, REM sleep, Circadian clock

circadian rhythm

n.
A daily rhythmic activity cycle, based on 24-hour intervals, that is exhibited by many organisms.

cir·ca·di·an rhythm

(sər-kā′dē-ən)
A daily cycle of biological activity based on a 24-hour period and influenced by regular variations in the environment, such as the alternation of night and day.
Did You Know? Why do you sometimes wake up on time even if your alarm clock doesn't ring? How do nocturnal animals know when it is time to wake up? It's because you—and most other animals—have a kind of internal clock that controls the cycle of the day's biological activities, such as sleeping and waking. These daily biological activities are known as circadian rhythms because they are influenced by the regular intervals of light and dark in each 24-hour day. While the process underlying circadian rhythm is not completely understood, it is mainly controlled by the release of hormones. The brain regulates the amount of hormone released in response to the information it gets from light-sensitive cells in the eye, called photoreceptors. Circadian rhythms can be disrupted by changes in this daily schedule. For example, biologists have observed that birds exposed to artificial light for a long time sometimes build nests in the fall instead of the spring. In humans who travel long distances by air, the local time of day no longer matches the body's internal clock, causing a condition known as jet lag.

circadian rhythm

The regular recurrence of life activities in 24-hour cycles.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.circadian rhythm - a daily cycle of activity observed in many living organisms
biological time - the time of various biological processes
Translations

cir·ca·di·an rhythm

n. ritmo circadiano, ref. a variaciones rítmicas biológicas en un ciclo de 24 horas.
References in periodicals archive ?
Circadian rhythms are a prominent and critical feature of cells, tissues, organs, and behavior that help an organism function most efficiently and anticipate things such as food availability.
Daily or circadian rhythms include the sleep-wake cycle, and rhythms in hormone release are controlled by a molecular clock that is present in every cell of the human body.
Circadian rhythms regulate a variety of physiological and metabolic processes in diverse organisms.
Women who have stronger circadian rhythms may experience lower risk for dementia, a study suggests.
Research published in the December 2011 issue of Annals of Neurology found that older women with weaker circadian rhythms and who tend to be at their most active later in the day were 80 percent more likely to develop MCI or dementia compared to women with more consistent circadian rhythms and who were active early in the day.
Wirz-Justice, who has led numerous investigative studies in the field and lectured on the role of circadian rhythms in affective disorders at the congress.
No one thought these findings might hold any relevance for humans, whose circadian rhythms were then widely believed to be relatively insensitive to light.
1,2) Such characteristics are controlled by circadian rhythms under the command of the organism's circadian pacemaker, also referred to as the "biological clock" The word circadian is taken from the Latin circa dies, meaning "around a day" and, in this instance, refers to the endogenous flee-running clock within the hypothalamus.
Hastings said that light therapy may have its application elsewhere because other neurological diseases such as Huntington's and Parkinson's are linked with the disruption of circadian rhythms.
Again, circadian rhythms were found in the speed of locomotion throughout the day and night.
Disruptions of circadian rhythms have health consequences, prevalent in this 24/7 jet-hopping world.
Melatonin, a hormone excreted by the pineal gland during sleep, regulates sleep and circadian rhythms (Srinivasan, Pandi-Perumal, Cardiniali, Poeggeler, & Hardeland, 2006).