Melatonin for Jet Lag Versus Everyday Sleeplessness: Two Different Questions
Melatonin is often treated as a general sleep aid. The research draws a sharper line: the evidence for jet lag looks different from the evidence for chronic sleep problems.
Melatonin occupies an unusual spot in the supplement world: it is a hormone the body produces itself, sold over the counter in many countries and reached for in two very different situations — crossing time zones and lying awake at home. The evidence for those two uses is not the same, and comparing them is instructive.
The jet lag case
A Cochrane review on melatonin and jet lag concluded that melatonin, taken close to the target bedtime at the destination, reduced jet lag symptoms in most of the included trials of eastward and westward flights crossing several time zones. The plausible mechanism is well described: melatonin acts as a timing signal for the internal clock, and after a long flight it is precisely the timing that is out of alignment.
The everyday sleeplessness case
For ordinary difficulty falling or staying asleep, the picture is thinner. The National Center for Complementary and Integrative Health summarizes the trial evidence as suggesting, at most, modest effects — studies point to people falling asleep somewhat faster on average, with effects small enough that their practical relevance is debated. NCCIH also notes open questions around long-term use, appropriate dosing and the notable gap between labeled and actual melatonin content found in some marketed products.
Why the comparison matters
The two situations differ in what is actually wrong. Jet lag is a clock problem, and melatonin is a clock signal — a reasonable match. Persistent poor sleep usually is not a clock problem; it has many possible drivers, from stress and stimulants to underlying conditions that belong in a doctor’s appointment rather than a supplement bottle.
The bottom line
For occasional long-haul travel, the evidence base for melatonin is comparatively solid. As a nightly answer to ongoing sleep trouble, it is weakly supported — and anyone reaching for it night after night has a better first step available: discussing the sleep problem itself with a physician.
Two practical notes round out the comparison. Product quality varies: analyses cited by NCCIH found that the melatonin content of tested products often deviated substantially from the label, in both directions. And timing matters more than dose — for jet lag, the studies used melatonin close to the destination bedtime, not whenever the traveler happened to remember it.