Advanced Melatonin Timing Calculator & Circadian Phase-Shift Planner

The Science of Circadian Phase Response & Melatonin Timing

Melatonin is a chronobiotic hormone produced by the pineal gland that signals biological night to the central circadian pacemaker located in the suprachiasmatic nucleus (SCN). Timing exogenous melatonin administration correctly relative to the Dim Light Melatonin Onset (DLMO) is critical for successfully shifting sleep-wake cycles.

Key Circadian Benchmarks

• Dim Light Melatonin Onset (DLMO): The gold-standard marker for internal circadian phase, usually occurring roughly 2 hours prior to habitual sleep onset.
• Phase Response Curve (PRC): Exogenous melatonin administered in the biological afternoon or early evening triggers a phase advance (earlier sleep timing), whereas morning administration triggers a phase delay.
• Core Body Temperature Minimum (Tmin): Occurs near the end of the biological night and represents the inflection point of the circadian rhythm.

Medical Disclaimer

This calculator is provided strictly for educational reference and self-monitoring exploration. Melatonin is biologically active even in very small microgram doses; always consult a qualified physician or sleep specialist before starting supplementation or attempting circadian realignment protocols.