Melatonin is the most misunderstood supplement in sleep. It isn't a sleeping pill — it's a timing signal, 'chemical darkness,' that tells your brain what time it is. Use it that way and it's genuinely useful; use it as a sedative and you're mostly just taking too much.
Melatonin signals biological night; it doesn't knock you out. That's why it shines for circadian problems — jet lag, delayed sleep phase, shift work — and only modestly helps ordinary insomnia (the sleep guidelines actually recommend against it for chronic insomnia, because as a hypnotic it barely works). Match it to a clock problem, not a can't-switch-off problem. Evidence ●●●○○
The classic MIT work found a physiological 0.3 mg dose restored sleep as well as 3 mg — while the higher dose pushed melatonin to unnatural levels that lingered into the day, causing grogginess. The 3–10 mg gummies on shelves are 10–30× physiological. For most purposes, 0.3–0.5 mg, timed correctly, is the target — more is not better, it's arguably worse. Evidence ●●●○○
To shift your clock earlier, take a small dose in the early evening (a few hours before your natural sleep time), not at bedtime. And beware quality: US analyses found actual melatonin content ranging from about −83% to +478% of the label, with some gummies containing unlabelled CBD or serotonin. Buy USP-verified, and use tiny doses. Evidence ●●●●○ on the quality problem
Right tool, right dose
Melatonin at 0.3–0.5 mg, timed right, is a real tool for jet lag and body-clock problems. As a nightly 10 mg 'sleeping pill' for ordinary insomnia, it's the wrong tool at the wrong dose.
The Sleep Guide