What is the Origin of Melatonin Release Cycle?

The term is derived from the Greek word melas (black) and tonos (tension/tone), referencing its role in skin darkening in some species and its discovery as a sleep-regulating hormone. The 'Release Cycle' specifically highlights the rhythmic, predictable nature of its secretion, which is a core tenet of chronobiology. Its clinical relevance in human health is extensive, spanning sleep, aging, and oxidative stress.

What is the Mechanism of Melatonin Release Cycle?

Light exposure, particularly blue light, is detected by specialized retinal ganglion cells, which transmit signals to the SCN. During darkness, the SCN signals the pineal gland to synthesize and release melatonin from its precursor, serotonin. The nocturnal rise in melatonin then signals darkness to the rest of the body, facilitating the transition to sleep and initiating nighttime repair processes, thereby coupling environmental light cues to internal physiological timing.

Melatonin Release Cycle

Meaning

The Melatonin Release Cycle is the endogenous, circadian rhythm-regulated secretion pattern of the hormone melatonin from the pineal gland, which is fundamentally controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus. Clinically, this cycle is critical for entraining the sleep-wake rhythm, modulating immune function, and exerting powerful antioxidant effects. A robust and timely nocturnal melatonin peak is a key biomarker of a healthy circadian system.