diurnal rhythm

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1. Pertaining to the daylight hours; opposite of nocturnal.
2. Repeating once each 24 hours, for example, a diurnal variation or a diurnal rhythm. Compare: circadian.
[L. diurnus, of the day]

diurnal rhythm

Etymology: L, diurnalis, of a day; Gk, rhythmos
patterns of activity or behavior that follow day-night cycles, such as breakfast-lunch-dinner schedules.

circadian rhythm

The diurnal cadence which, in humans (without cyclical cues provided by natural light), is 24.1–24.2 hours (older data had put this figure at 25.4 hours). Photoperiodic information from the eyes synchronises the circadian pacemaker with the light-dark cycle; circadian rhythm affects drug metabolism (e.g., antacids, halothane), serum levels of various substances (in particular adrenocortical hormones) that are routinely measured to detect and monitor disease, physiologic activities (e.g., blood pressure, myocardial blood flow and oxygen demand), psychosomatic disease and sleep cycles, cell division, haematopoiesis and natural killer cell activity.

diurnal rhythm

a pattern of activity based upon a 24-hour cycle, in which there are regular light and dark periods. See also CIRCADIAN RHYTHM.
References in periodicals archive ?
Evidence of a diurnal rhythm was indicated by a significant cosinor model fit.
as a previous study showed environmental changes affect the diurnal rhythm of sports performance [16]).
IC placed in the uterotubal junction was successfully to measure intrauterine temperature and detected diurnal rhythm.
Diurnal rhythms may persist when the organism is placed in an environment devoid of time cues, such as constant light or constant darkness.
These data are in agreement with recent observations of similar hepcidin diurnal patterns for individuals with and without food intake and corroborate previous findings that transcriptional regulators related to genes involved in diurnal rhythm are potentially significant modulators of hepcidin expression (7, 15).
It is demonstrated that the plasma glucose level has a diurnal rhythm in rats, which depends on the circadian secretion of melatonin or the control mechanism of suprachiasmatic nucleus on hepatic glucose delivery (6,13).
Estimates of period length close to 24 h were considered evidence of a diurnal rhythm, provided that all model parameters were estimated with high statistical significance (P < 0.
A 24-1 glass tank (W:D:H = 40:20:30 cm) was used to monitor the diurnal rhythm and behavior (swimming or not swimming) of the medusae.
Circulating proprotein convertase subtilisin kexin type 9 has a diurnal rhythm synchronous with cholesterol synthesis and is reduced by fasting in humans.
The biggest increase of serum FGF21 concentrations started around midnight (0000), reached its peak at around 0500 of the second day, and then slowly declined to a nadir in the afternoon, suggesting that FGF21 secretion is regulated by the diurnal rhythm in humans.
14) reported that healthy nonobese individuals who fasted for 3 days developed a diurnal rhythm in ghrelin characterized by low concentrations in the morning with subsequent increases in the afternoon and at midnight.
None of these crystals appeared to be deposited in a diurnal rhythm.