What is the Origin of Melatonin Secretion Cycle?

This term is derived from chronobiology and neuroendocrinology, following the identification of melatonin and its role as a neurohormone linking environmental light-dark cycles to internal biological rhythms. The pineal gland's function as a "third eye" sensing light was a pivotal discovery in understanding human biological timing.

What is the Mechanism of Melatonin Secretion Cycle?

The secretion cycle is governed by the suprachiasmatic nucleus (SCN), the body's master clock, which receives direct light input from the retina via the retinohypothalamic tract. In darkness, the SCN signals the pineal gland to synthesize melatonin from serotonin, a process inhibited by blue light exposure. Melatonin then acts on MT1 and MT2 receptors in the SCN and other brain regions to promote sleep onset and consolidate the circadian rhythm.

Melatonin Secretion Cycle ∞ Area

Melatonin Secretion Cycle

Meaning

The precise, circadian-regulated pattern of synthesis and release of the indoleamine hormone melatonin from the pineal gland, which serves as the primary hormonal signal for darkness and is central to the synchronization of the sleep-wake cycle. The cycle is characterized by a sharp increase in the evening, a peak in the middle of the night, and a rapid decline toward morning. Maintaining the integrity of this cycle is crucial for robust sleep architecture and chronobiological health.