Intermediate
Technical
In the Industry Vocabulary Test
circadian rhythm
Pronunciation: sir-KAY-dee-an
Endogenous biological cycles of approximately 24 hours that regulate physiological processes and hormone secretion.
Full Definition
Circadian rhythms are internally generated biological cycles with periods of approximately 24 hours that coordinate physiological processes with environmental light-dark cycles. In neuroendocrinology, these rhythms regulate the timing of hormone secretion, including cortisol, melatonin, and growth hormone. The master circadian clock is located in the suprachiasmatic nucleus of the hypothalamus and synchronizes peripheral clocks throughout the body.
Usage
Usage note: Note the approximately 24-hour period; distinguish from ultradian (shorter) and infradian (longer) rhythms.
In Context
- "Disruption of circadian rhythm affects cortisol secretion patterns." — Sleep disorder research paper
- "The patient's circadian rhythm was assessed using continuous hormone monitoring." — Clinical evaluation report
Also known as
biological clock
daily rhythm
Contrasted with
arrhythmic
ultradian rhythm
Don't confuse with
ultradian rhythm
infradian rhythm