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Circadian Phase Locking

Meaning

Circadian Phase Locking refers to the critical process of precisely synchronizing the body’s endogenous master biological clock, located in the suprachiasmatic nucleus (SCN) of the hypothalamus, to the external 24-hour environmental cycle. This synchronization is achieved through the use of external time cues, known as zeitgebers, with the light/dark cycle being the most potent. Robust phase locking is essential for aligning the rhythmic secretion of nearly all hormones, including cortisol and melatonin, and ensuring metabolic processes are timed for optimal function. Desynchrony, or a loss of locking, is a major contributor to metabolic dysfunction and hormonal dysregulation.