circadian rhythm

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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 ?
Phase advance is the resetting of the circadian clock earlier in time so that all the circadian rhythms of the body occur earlier.
In fruit flies, that gene, per, is a major cog in the circadian clock.
In the new study, researchers have identified how a fundamental biological process called protein synthesis is controlled within the body's circadian clock - the internal mechanism that controls one's daily rhythms.
Melatonin is a chronobiotic; that is, it has the ability to set and reset the body's circadian clock.
After a few months, they're totally blind, But their response to light, as far as the circadian clock goes, is absolutely normal," says Aziz Sancar of the University of North Carolina School of Medicine in Chapel Hill.
The research examined the role of specialized photosensitive cells in the retina-called ipRGCs-that don't have a major role in vision, but detect light and send messages to a part of the brain that helps regulate the body's circadian clock.
Tumor cell circadian clock genes are rhythmically expressed in coordination with rhythmic circadian growth and thereby may represent new therapeutic targets: Abstract 698
While the "Science" study confirms that melanopsin can transmit information to the circadian clock, future studies will focus on identifying the relative contributions of other molecules to circadian clock maintenance, Ruby and O'Hara noted.
Animals possess a number of biological clocks, the most well known being the circadian clock, which establishes day-long patterns of behavior.
They suspect that high-fat diets might throw the circadian clock out of whack, which could be counteracted by increased SIRT1 activation.
Interestingly, the circadian clock appears to control when c-fos and jun-B will respond.
Although many immune responses are known to follow daily oscillations, the role of the circadian clock in the immune response to acute infections has not been understood," said Sassone-Corsi, the Donald Bren Professor of Biological Chemistry.