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Evening Cortisol Suppression

Meaning

Evening Cortisol Suppression is the necessary physiological process where the secretion of the stress hormone cortisol significantly decreases during the late afternoon and evening hours, facilitating the transition to sleep. This natural decline is a critical component of the normal diurnal cortisol rhythm, which is governed by the HPA axis and the circadian clock. Failure to achieve adequate suppression, often due to chronic stress or late-day environmental stimuli, results in central nervous system hyperarousal and subsequent sleep onset or maintenance insomnia.