What is the Origin of Nighttime Melatonin Signaling?

This term is rooted in neuroendocrinology and chronobiology, describing the hormone's function ("melatonin signaling") during its peak release period ("nighttime"). Melatonin itself is derived from the Greek melas (black) and tonos (tone or tension). The discovery of its light-suppression mechanism established its role as the darkness hormone.

What is the Mechanism of Nighttime Melatonin Signaling?

Darkness stimulates the suprachiasmatic nucleus (SCN) to signal the pineal gland, initiating the enzymatic conversion of serotonin to melatonin, which is then released into the circulation. Melatonin binds to its receptors in the SCN to reinforce the central clock's timing and acts peripherally to lower body temperature and decrease alertness, facilitating sleep onset and maintenance. Disruption by light exposure at night suppresses this essential signal, leading to circadian misalignment. The MT1 and MT2 receptors mediate the chronobiotic effects.

Nighttime Melatonin Signaling ∞ Area

Nighttime Melatonin Signaling

Meaning

Nighttime melatonin signaling refers to the crucial process by which the pineal gland releases the hormone melatonin in a darkness-dependent, circadian-controlled manner, and how this hormone then acts on its receptors (MT1 and MT2) throughout the body. This signal is the primary endocrine messenger of darkness, governing the synchronization of the sleep-wake cycle and regulating numerous physiological processes that occur during rest. Intact signaling is essential for sleep quality, immune function, and antioxidant defense.