What is the Origin of Cortisol Trough?

The term combines 'cortisol,' the primary glucocorticoid, with 'trough,' an engineering or topographical term denoting the lowest point of a wave or curve. This descriptive phrase precisely captures the nadir of the hormone's cyclical secretion pattern, a phenomenon well-documented in clinical endocrinology. The concept is central to assessing adrenal fatigue and circadian health.

What is the Mechanism of Cortisol Trough?

During the evening and early sleep cycle, the hypothalamic-pituitary-adrenal (HPA) axis actively suppresses the release of corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH), leading to the lowest physiological production of cortisol by the adrenal glands. Achieving this low baseline concentration is paramount for the restorative processes of sleep, including the unimpeded pulsatile secretion of Growth Hormone and the re-calibration of immune function.

Cortisol Trough ∞ Area

Cortisol Trough

Meaning

The Cortisol Trough is the lowest point in the diurnal rhythm of the stress hormone cortisol, typically occurring late at night or during the initial hours of the nocturnal sleep cycle. This minimum concentration is a critical marker of HPA axis regulation and adrenal function, indicating the body’s successful transition into a deep, restorative, and parasympathetic-dominant phase. A well-defined trough is essential for proper circadian synchronization and subsequent morning cortisol awakening response.