Melatonin

Meta-analyses confirm reduced sleep latency and strong effects on circadian problems — jet lag, shift work, delayed sleep phase. The average latency improvement in ordinary insomnia is real but modest (~7 minutes).

Melatonin is the most misunderstood popular supplement, and the misunderstanding is baked into how it is sold. It sits on the shelf next to sleep aids, gets dosed like a sleep aid, and disappoints people who expected a sleep aid — because it is not one. Melatonin is the hormone your brain uses to announce that night has arrived. Supplementing it does not sedate you; it moves the announcement.

Read that way, the evidence sorts cleanly. Where the problem is timing — jet lag, shift work, the delayed sleep phase of night owls — melatonin has some of the best data in sleep medicine, with a Cochrane review finding it remarkably effective for jet lag when taken at the destination bedtime. Where the problem is garden-variety insomnia, meta-analysis finds it shaves an average of about seven minutes off sleep latency: real, but a fraction of what prescription hypnotics or CBT-I deliver.

Dosing is where practice diverges furthest from evidence. Receptor studies and dose-response trials point to 0.5-1 mg as sufficient — often more effective than the 5-10 mg gummies that dominate the market, which can leave morning grogginess and spillover of elevated melatonin into the next day. More timing signal is not more sleep. Equally important is the quality-control problem: analyses of retail products have found actual content ranging from a fraction of the label to several times it, so third-party-tested brands matter more here than almost anywhere.

Safety at low doses and reasonable durations looks good, with grogginess and vivid dreams the common complaints, though long-term nightly use in healthy adults is less studied than the sales volume implies. The best use is surgical: shift the clock when the clock is the problem, at the smallest dose that works — and treat chronic sleeplessness as the behavioral and light-exposure problem it usually is.

How it works

Melatonin is the hormone your pineal gland releases as light fades, signaling circadian night to every clock-bearing tissue. Supplemental melatonin acts on MT1/MT2 receptors to phase-shift that clock and modestly lower alertness — a timing signal, not a hypnotic, which is why dose timing matters more than dose size.