Should I take melatonin? How much actually works?

Melatonin at 0.5–1 mg taken 30–60 minutes before the desired sleep time is effective for resetting circadian timing in jet lag and shift work, but is less useful for general insomnia in men with normal circadian rhythms, and the standard 5–10 mg doses sold in US pharmacies are 5–20× the physiologically relevant dose, potentially causing morning grogginess and blunted natural melatonin production with regular use (Ferracioli-Oda et al., PLOS ONE, 2013).

Melatonin is a timing signal, not a sedative. It signals the brain that darkness has arrived and the biological clock should shift toward sleep. At supraphysiological doses (3–10 mg), it does have mild sedative-adjacent effects, but these are not the mechanism it is biologically designed for. European regulatory bodies cap melatonin at 2 mg per dose for this reason. Men who take 10 mg melatonin nightly and find it "works" are experiencing a sedative effect, not the precision circadian-timing effect that makes melatonin genuinely useful.

Honesty Scale: Solid (1) for melatonin at low doses for circadian resetting. Early (3) for melatonin as a general sleep-quality supplement in men with normal circadian rhythms.

What to do: Use melatonin at 0.5–1 mg for jet lag (take it at the destination bedtime starting the day of travel), shift work adjustment, and transitioning from a late sleep schedule to an earlier one. Do not use 5–10 mg doses nightly, you are taking a drug at 10–20× the physiological dose without corresponding benefit and with possible feedback suppression of your own melatonin production.

For the full picture, read The Sleep Hygiene Deep Dive