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Biological Cycles

Meaning

Endogenous, recurring patterns of physiological and biochemical processes that oscillate over predictable timeframes, dictating the timing and magnitude of hormonal secretion and cellular activity. The most recognized cycle is the circadian rhythm, approximately 24 hours, which profoundly influences the sleep-wake cycle, cortisol release, and melatonin production. Other critical cycles include ultradian (less than 24 hours) and infradian (longer than 24 hours, like the menstrual cycle).