📖 Sleep Science

Melatonin: Low Dose vs High Dose — The Real Science

By BedtimeCalc Sleep Science Team · · ⏱ 7 min read · 🔬 Evidence-based

Melatonin is the most widely used sleep supplement globally — and the most widely misused. The doses on most store shelves (5–10mg) are 10–20× higher than the physiological dose shown to be effective in research. This guide explains what melatonin actually does, the correct dose, and the right timing.

🏛️ Harvard Sleep Medicine aligned
📋 NSF 2022 guidelines
🔬 Peer-reviewed sources
Reviewed April 2026
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What Melatonin Actually Does

Melatonin is not a sedative. It does not directly cause sleep — it is a darkness signal that tells your circadian clock it is night. The effect is chronobiological (clock-shifting) rather than sedative. This is why taking 10mg of melatonin does not feel like a sleeping pill. It shifts your clock timing — it does not knock you out.

🔬 The Dose Problem

Research by Dr. Richard Wurtman at MIT found that physiological levels of melatonin (the amount your brain naturally produces) are 0.1–0.3mg. Supplements at 0.5mg still effectively saturate melatonin receptors. Doses of 5–10mg do not produce proportionally better effects — they just remain in your system longer and can cause next-day grogginess.

When to Take Melatonin

For sleep onset delay (general insomnia): 0.5mg taken 30 minutes before target bedtime. Do not take it if you are already in bed — it will have already peaked. Take it while still up and winding down.

For jet lag (eastward travel): 0.5mg at 10 PM destination time for 3 consecutive nights after arrival. This accelerates clock advancement.

For jet lag (westward travel): Melatonin is less effective for westward travel (clock delay). Light exposure management is more useful.

For delayed sleep phase (night owls): 0.5mg taken 5–6 hours before your natural sleep time (so for a midnight sleeper: 6–7 PM) can gradually advance the clock over weeks. Requires consistency.

When NOT to Use Melatonin

Melatonin is not appropriate as a long-term solution to poor sleep hygiene or behavioural sleep problems. It will not fix the consequences of caffeine at 4 PM, phones in bed, or inconsistent schedules. It is a tool for specific circadian timing challenges — not a substitute for the habits that determine sleep quality.

🌙 Fix Your Sleep Schedule

Use our 7-day reset plan combined with appropriate melatonin timing for the fastest results.

Read Reset Plan →
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BedtimeCalc Sleep Science Team
Our recommendations are grounded in peer-reviewed sleep research, including landmark work by Kleitman & Aserinsky (1953) and National Sleep Foundation guidelines. Every page is reviewed before publication and updated when new research emerges.
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Frequently Asked Questions

Research consistently shows 0.5mg is the effective dose for most sleep applications. Higher doses (5–10mg) do not produce proportionally better results and can cause next-day grogginess due to extended duration of action.

For sleep onset: 30 minutes before your target bedtime while still awake. For jet lag going east: at 10 PM destination time for 3 nights after arrival. Timing matters more than dose for melatonin effectiveness.