Calculator

Melatonin Timing Calculator

Melatonin is a clock signal, not a sedative. Get the dose and the exact clock time that match your goal, built from an estimate of your own circadian phase.

Your sleep schedule

When do you usually fall asleep?

The time you actually drift off on free days, not when you get into bed.

Target sleep time

When you want to be falling asleep instead.

What are you trying to do?

Fall asleep at my usual bedtime Shift my whole schedule earlier Prepare for eastward jet lag

Chronotype check

Five questions adapted from the reduced Morningness-Eveningness Questionnaire. Your chronotype adjusts where the calculator places your dim light melatonin onset (DLMO) relative to your bedtime.

1. If you were entirely free to plan your day, what time would you get up?

2. During the first half hour after waking, how tired do you feel?

3. At what time in the evening do you feel tired and in need of sleep?

4. At what time of day do you feel at your best?

5. Do you consider yourself a morning type or an evening type?

How this works

Melatonin is a chronobiotic: a signal that tells the master clock in the suprachiasmatic nucleus where evening is, acting through MT1 and MT2 receptors. It is a weak hypnotic at best, so when you take it matters far more than how much. The reference point is your dim light melatonin onset (DLMO), the time your pineal gland starts secreting melatonin under dim light. DLMO sits roughly 2 to 3 hours before habitual sleep onset; this calculator places it 3.0 hours before for morning types, 2.5 for intermediate, and 2.0 for evening types, using a 5-item chronotype score. Questionnaire chronotype correlates with measured DLMO at roughly r = 0.5 to 0.7 (Kantermann 2015), so treat the estimate as a starting point, not a lab value.

For falling asleep at your usual bedtime, the calculator recommends 0.3 to 0.5 mg immediate release, 30 to 60 minutes before bed. Immediate-release melatonin reaches peak blood levels in about 30 to 45 minutes and has an elimination half-life of roughly 40 to 60 minutes, so a small dose taken shortly before bed mimics the natural nocturnal rise. Doses of 0.3 to 0.5 mg produce blood levels in the normal nighttime physiologic range; 3 to 10 mg produces levels ten or more times higher without working better for sleep onset, and the excess is still circulating the next morning (spillover), which can blunt the phase shift and cause grogginess. A meta-analysis of trials at 10 mg or more found significantly increased drowsiness, headache, and dizziness (Menczel Schrire 2022).

For shifting sleep earlier, the calculator uses the phase response curve to 0.5 mg melatonin (Burgess 2010): advances are largest when the dose lands several hours before DLMO, so it schedules 0.5 mg at 5 hours before your estimated DLMO, with a 4 to 6 hour acceptable window. Combined with a bedtime that steps earlier and bright light on waking, this yields realistic advances of about 30 to 60 minutes per day; the multi-day plan steps 45 minutes per day and moves the melatonin time with the schedule. The same logic drives the eastward jet lag plan (1 hour of advance per pre-flight day, then bedtime dosing at the destination). In clinically diagnosed delayed sleep-wake phase disorder, 0.5 mg an hour before desired bedtime plus scheduled sleep improved sleep onset in a randomized trial (Sletten 2018).

Supplement quality is a real problem. A content analysis of 31 melatonin products found actual melatonin ranging from 83% below to 478% above the label, and 26% contained serotonin (Erland and Saxena 2017). Choose a third-party tested product (USP Verified or equivalent). Use immediate release for sleep onset and phase shifting; extended release only addresses staying asleep. Melatonin is not for children without clinician input, and this tool is educational, not diagnostic; suspected circadian rhythm disorders deserve a clinician.

Related calculators

Caffeine Clearance finds the caffeine cutoff time that protects the bedtime you are working toward.
Supplement Timing Optimizer schedules melatonin alongside the rest of your stack.

References

Burgess HJ, Revell VL, Molina TA, Eastman CI. Human phase response curves to three days of daily melatonin: 0.5 mg versus 3.0 mg. J Clin Endocrinol Metab. 2010;95(7):3325-3331.

Sletten TL, Magee M, Murray JM, et al. Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder: a double-blind, randomised clinical trial. PLoS Med. 2018;15(6):e1002587.

Erland LA, Saxena PK. Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. J Clin Sleep Med. 2017;13(2):275-281.

Menczel Schrire Z, Phillips CL, Chapman JL, et al. Safety of higher doses of melatonin in adults: a systematic review and meta-analysis. J Pineal Res. 2022;72(2):e12782.

Kantermann T, Sung H, Burgess HJ. Comparing the Morningness-Eveningness Questionnaire and Munich ChronoType Questionnaire to the dim light melatonin onset. J Biol Rhythms. 2015;30(5):449-453.