circadian rhythm

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Related to diurnal cycle: diurnal rhythm, Circadian cycle

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 ?
The international research team led by Matthias Grott determined the increase and decrease of the surface temperature over the course of the asteroids roughly seven-and-a-half-hour diurnal cycle. This was accomplished by measuring the infrared radiation emitted by the surface during the day and at night, using the MARA radiometer.
The variable-resolution FV3-based model is shown to possess global forecast skill comparable with that of the operational GFS while quantitatively improving skill and better representing the diurnal cycle within the high-resolution area compared to the uniform mesh simulations.
The monthly FFT results of New York City display two distinct patterns in Figure 2: in summer months (May to August), two large spikes occur at k = total number of days (around 30) and low frequency f= 2 or greater suggesting both diurnal cycle and cyclic pattern with period of 15 days or less in one month.
In this study the diurnal cycle of the observed wind direction in the Kurzeme coastal stations of the Baltic Proper is analysed.
Future astronauts might descend into a hollow, long-frozen lava tube on the Moon to gain shelter from cosmic rays and small impact events, and to moderate the extreme temperature swings (300[degrees]C or 540[degrees]F) that the surface endures over a 29V2-day-long lunar diurnal cycle.
For instance, the topographic influence is evident in the diurnal cycle of MCSs, whereas the influence of the ITCZ may be revealed in intra-annual time scales, which in turn may be modulated at intra-annual time scales for phenomena such as the 3- to 11-year quasi-oscillating ENSO.
Today, Melbourne's city centre population is closing in on 100,000 residents while the metropolitan area population is four million and is vibrant throughout the diurnal cycle; just 20 years ago, it was an example of a doughnut city and there were fewer than a third of the today's population.
Among their topics are a genome-wide analysis of cyanobacterial evolution: the example of Synechococcus, the RNA-seq based transcriptomic analysis of single cyanobacterial cells, transcriptomic and proteomic analysis to understand systems-level properties of diurnal cycle in nitrogen-fixing cyanobacteria, metabolic engineering and systems biology for free fatty acid production in cyanobacteria, and ethanol production in cyanobacteria: the impact of omics of the model organism Synechocystis on yield enhancement.
Since the new system is separate from all other lighting controls in the building, a central controller is able to maintain the diurnal cycle for all 48 patient rooms, while six-button keypads were installed in each room that would all be fed with vital power to keep the cycles intact during any power interruption.
On shorter timescales, cloudiness and heavy rainfall over tropical and subtropical South America, associated with convective activity, follow a diurnal cycle (de Angelis et al., 2004; Poveda et al., 2005; Bendix et al., 2006).