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Pre-Dawn Hormone Nadir

Meaning

The Pre-Dawn Hormone Nadir refers to the specific time point, typically occurring in the deep sleep hours just before the onset of the Cortisol Awakening Response, when the concentration of certain key circulating hormones reaches its lowest level of the 24-hour cycle. Cortisol, for example, is at its lowest point during this window, reflecting the maximal rest and recovery state of the hypothalamic-pituitary-adrenal (HPA) axis. This physiological minimum is a crucial indicator of a properly regulated circadian rhythm and HPA axis function, facilitating the restorative processes of sleep. A disruption of this nadir, such as an elevated pre-dawn cortisol level, can indicate chronic stress or sleep disturbance.