Melatonin Dosing & Timing Calculator

The Science of Melatonin and Circadian Rhythms

Melatonin is a hormone produced naturally by the pineal gland in response to darkness. It acts as the key signal to synchronize your internal master clock (the suprachiasmatic nucleus) with the 24-hour day-night cycle.

In clinical sleep science, natural melatonin production begins during Dim Light Melatonin Onset (DLMO), which typically occurs 2 to 3 hours before natural sleep onset.

Exogenous melatonin (supplements) can affect your sleep cycle through two distinct physiological mechanisms:

1. The Circadian Phase Shift (Chronobiotic Effect)

If you need to shift your sleep schedule earlier (phase advance), taking a low physiological dose (0.3 mg to 0.5 mg) is highly effective.

Based on the Circadian Phase Response Curve (PRC), exogenous melatonin shifts your internal clock earliest when taken 5 to 7 hours before your target bedtime (which is several hours before natural DLMO). Taking large doses too early is not recommended, as it can cause daytime fatigue.

2. Physical Sleep Induction (Hypnotic Effect)

If you are looking for an immediate feeling of drowsiness, a pharmacological dose (1.0 mg to 3.0 mg) should be taken 1 to 2 hours before bedtime.

At this timing, the supplement acts directly as a mild sedative to help you fall asleep. However, high-dose sedative use does not shift your underlying circadian phase as effectively and can lead to morning sleepiness.

Matching Dosing to Your Chronotype

Your chronotype represents your natural circadian peak.

• Morning Larks have an early DLMO and require minimal shifting.
• Night Owls have delayed DLMO peaks. When an owl attempts to wake up early, their body undergoes "social jet lag." Low-dose melatonin timed 6 hours before bedtime is the primary clinical tool to pull their circadian phase earlier.