What is the Origin of Pre-Dawn Cortisol Peak?

The term is descriptive, pinpointing the time of occurrence, pre-dawn, and the hormonal event, cortisol peak. It is a well-established phenomenon in chronobiology and endocrinology, demonstrating the strong circadian control over the HPA axis. The CAR is distinct from stress-induced cortisol release, reflecting an anticipatory, scheduled physiological preparation for the day.

What is the Mechanism of Pre-Dawn Cortisol Peak?

The peak is centrally driven by the suprachiasmatic nucleus (SCN) signaling the paraventricular nucleus (PVN) in the hypothalamus to increase the release of corticotropin-releasing hormone (CRH). This cascade ultimately stimulates the adrenal glands to secrete cortisol in a rapid surge. Cortisol then acts to increase hepatic gluconeogenesis and enhance catecholamine sensitivity, preparing the body for the metabolic demands of the waking state.

Pre-Dawn Cortisol Peak ∞ Area

Pre-Dawn Cortisol Peak

Meaning

The Pre-Dawn Cortisol Peak, also known as the Cortisol Awakening Response (CAR), is the sharp, pulsatile increase in the adrenal stress hormone cortisol that naturally occurs in the final hours of sleep. This physiological event is a critical component of the body’s circadian rhythm, serving to mobilize energy stores and prime the central nervous system for imminent wakefulness. A healthy peak indicates a robust and responsive Hypothalamic-Pituitary-Adrenal (HPA) axis and is essential for optimal morning alertness and metabolic function. An absent or blunted peak can be a clinical indicator of HPA axis dysfunction or chronic stress.