What is the Origin of Melatonin Onset Timing?

The term combines 'melatonin,' the hormone responsible for signaling darkness, with 'onset timing,' emphasizing the exact start of its nocturnal rise. The DLMO assay, developed in chronobiology, represents a scientific attempt to capture the internal timing mechanism, which is often misaligned with external clock time in modern life. This measurement provides objective data for personalizing sleep and light hygiene recommendations.

What is the Mechanism of Melatonin Onset Timing?

The mechanism is controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus, the body's master clock, which receives light input from the retina. As environmental light diminishes, the SCN signals the pineal gland to synthesize and release melatonin, which then acts on receptors throughout the body to promote sleepiness and signal the beginning of the biological night. A delayed or advanced DLMO directly correlates with common sleep disorders and can be influenced by light exposure and hormonal shifts.

Melatonin Onset Timing ∞ Area

Melatonin Onset Timing

Meaning

Melatonin Onset Timing, clinically referred to as Dim Light Melatonin Onset (DLMO), is the precise physiological time point when the pineal gland begins to significantly increase its secretion of the hormone melatonin in anticipation of sleep. This specific timing serves as the most reliable biological marker for an individual’s intrinsic circadian rhythm, or ‘biological night.’ Understanding an individual’s DLMO is essential in chronotherapy for diagnosing and managing circadian rhythm sleep-wake disorders.