Melatonin: what it does and does not do for sleep

Melatonin is a timing signal, not a sedative — it tells your body it's nighttime and helps shift the circadian clock, rather than directly forcing unconsciousness the way a sleep medication does. This is why it works better for shifting sleep timing (jet lag, shift work) than for treating chronic insomnia in someone whose schedule is otherwise consistent.

Dosing counterintuitively skews low: doses far smaller than what's sold in many over-the-counter capsules (often 10mg or more) are typically sufficient to produce a timing effect, and some research suggests higher doses don't scale up the benefit proportionally.

Timing relative to your target bedtime matters more than most people treat it — taken too close to bedtime, it may have little effect on that night's sleep onset since the signal needs lead time to shift the internal clock.

It's not a substitute for evaluating an underlying sleep disorder. Persistent poor sleep despite consistent melatonin use is a reason to look for an underlying cause — including sleep apnea — rather than escalate the dose.