What actually helps jet lag? Timing beats pills, and the winner is melatonin

Jet lag is not tiredness — it is a clock problem. Your body's internal rhythm is still keeping time in the city you left, out of step with the day and night where you have landed [s1]. That distinction decides what works. The interventions that actually help are the ones that move the clock: correctly timed melatonin and correctly timed light. The ones that mostly disappoint are the ones that only chase the symptom.

What the trials say about melatonin

The strongest evidence sits with melatonin, and it is unusually consistent for this field. A Cochrane review pooled ten randomised trials in travellers, airline staff and military personnel [s1]. Nine of the ten found that melatonin, taken close to the target bedtime at the destination — between 10pm and midnight — reduced jet lag after flights crossing five or more time zones [s1]. That is a rare thing in sleep research: near-unanimous trials pointing the same way.

The dosing detail matters because more is not better. Daily doses between 0.5 and 5mg were similarly effective, with the difference that people fell asleep faster and slept better on 5mg than on 0.5mg [s1]. Doses above 5mg appeared to be no more effective [s1]. So the useful takeaways are practical: the drug earns its keep on longer, multi-time-zone trips rather than a single hop; the timing — near destination bedtime — is doing much of the work; and there is no case for megadosing.

Two conditions define where melatonin helps. It is for crossing several time zones, not one or two, and the benefit is tied to taking it at the right local hour [s1]. Swallowed at the wrong time, melatonin can shift the clock the wrong way — which is the whole reason timing, not dose, is the variable to get right.

Light is the other half of the fix

Melatonin is one lever; light is the other, and arguably the more powerful one. Light is the dominant signal the body uses to set its clock, which is why clinical guidance on jet lag centres on managing light exposure alongside melatonin rather than reaching for sedatives [s2]. The principle is that seeking bright light at some times of day and avoiding it at others nudges the internal clock toward destination time, and the right direction depends on which way you have flown [s2][s3].

The rough rule most travellers can use: eastward travel requires advancing the clock, which generally means seeking morning light and protecting yourself from late-evening light at the destination, while westward travel requires delaying it, which tends to favour evening light [s3]. Eastward trips are usually the harder adjustment [s3]. Getting outdoors at the destination, rather than staying shuttered in a hotel, is one of the simplest ways to put that signal to work.

The reason light is worth the effort is that the clock does not snap to a new time zone; it drifts into alignment gradually, and left to itself that realignment takes days [s2]. Melatonin and well-timed light are the two ways to hurry it along and shorten the days spent feeling wrong [s2][s3]. Used together, in the same direction, they pull harder than either alone — the melatonin marking bedtime, the light marking the destination's day.

What does not fix the clock

This is where the popular remedies fall down. A sleeping pill can buy a night of sleep on the plane or in an unfamiliar bed, but it does nothing to realign the underlying rhythm, so the core problem persists [s2]. Alcohol is worse than neutral: a nightcap fragments sleep later in the night, as the site's review of alcohol and sleep architecture sets out. And no supplement stack substitutes for the two interventions with actual trial support behind them.

The practical version

For a long eastward trip across several time zones, the evidence-based plan is compact: take melatonin at your destination bedtime, keep the dose modest — anywhere from 0.5 to 5mg, since higher does not help — and use light deliberately, chasing it or avoiding it depending on your direction of travel [s1][s3]. Shift your watch, and your meals and sleep, to destination time on arrival. For the deeper mechanics of how light and the body clock interact, see the site's coverage of evening light and the circadian system. None of this is medical advice, and anyone with a health condition or on regular medication should check before adding melatonin.

Sources

• Melatonin for the prevention and treatment of jet lag — Cochrane Database of Systematic Reviews, 2002-04-22
• Jet Lag — New England Journal of Medicine, 2010-02-04
• How to Travel the World Without Jet Lag — Sleep Medicine Clinics, 2009-06-01