Skip to main content

Nocturnal Hormonal Suppression

Meaning

Nocturnal hormonal suppression describes the natural, physiologically necessary reduction in the circulating levels of specific hormones that occurs during the sleep period, primarily governed by the body’s circadian rhythm. Key hormones subject to this suppression include cortisol, which reaches its nadir during the middle of the night, and often thyroid-stimulating hormone (TSH). This period of suppression is crucial for allowing the body’s repair and regenerative processes, such as growth hormone and melatonin secretion, to dominate. Disruption of this nocturnal pattern, such as elevated cortisol or TSH at night, is a clinical marker of circadian misalignment and chronic stress.