What is the Origin of Cortisol Cycles?

The term combines "cortisol," the name of the primary human stress hormone derived from the adrenal cortex, and "cycles," which denotes a recurring sequence of events. The rhythmic nature of cortisol release is fundamentally linked to the body's master biological clock, the suprachiasmatic nucleus, which drives the circadian system.

What is the Mechanism of Cortisol Cycles?

The cycle is regulated by the pulsatile release of Adrenocorticotropic Hormone (ACTH) from the pituitary gland, which is itself controlled by Corticotropin-Releasing Hormone (CRH) from the hypothalamus. This HPA axis control ensures that cortisol levels are highest when the body anticipates the metabolic demands of the day and lowest during periods of rest. Chronic stress or HPA axis dysfunction can disrupt these normal cycles, leading to adverse physiological consequences related to sleep, immunity, and metabolic regulation.

Cortisol Cycles

Meaning

Cortisol Cycles refer to the predictable, endogenous rhythmic fluctuations in the secretion and circulating levels of the glucocorticoid hormone cortisol over a 24-hour period. This circadian rhythm is a key component of the Hypothalamic-Pituitary-Adrenal (HPA) axis, governing energy mobilization and stress response. Clinically, the cycle is characterized by a peak shortly after waking, known as the Cortisol Awakening Response, and a gradual decline throughout the day to its nadir late at night.