What is the Origin of Term 2?

The concept is rooted in chronobiology and endocrinology, specifically relating to the body's innate circadian rhythm, which is governed by the suprachiasmatic nucleus (SCN) in the hypothalamus. The rhythmic nature of cortisol was established through decades of physiological studies measuring plasma and salivary hormone levels across a full day. This understanding allows clinicians to assess the functional capacity and regulatory status of the adrenal glands.

What is the Mechanism of Term 2?

The SCN receives light signals and synchronizes the HPA axis activity, driving the pulsatile release of cortisol. The morning peak mobilizes glucose and prepares the body for daily activity, while the evening trough permits the onset of melatonin secretion and facilitates sleep initiation. Disruptions to this delicate mechanism, often due to chronic psychological or physical stress, can lead to persistent elevations or blunting of the curve, impacting metabolic and immune health.

Term 2 ∞ Area

Term 2

Meaning

The Cortisol Rhythm, often referred to as the diurnal cortisol curve, describes the predictable 24-hour pattern of cortisol secretion from the adrenal glands. This rhythm is typically characterized by a sharp peak shortly after waking, known as the Cortisol Awakening Response (CAR), followed by a gradual decline throughout the day, reaching its lowest point before sleep. A healthy rhythm is crucial for maintaining energy levels, regulating sleep-wake cycles, and ensuring proper immune surveillance. Deviations from this expected pattern are significant clinical indicators of HPA axis dysfunction.