Recovery and Travel: Managing Jet Lag
Light timing and melatonin for crossing time zones, and what the Cochrane review actually found.
Jet lag is the price of moving faster than your internal clock can adjust. Fly across several time zones and your body’s circadian rhythm — which governs sleep, alertness, digestion, and hormone release — stays anchored to where you came from while the local clock insists otherwise. The result is the familiar misery of being wide awake at 3 a.m. and foggy at noon. The reassuring part is that a few tactics, grounded in circadian biology, genuinely help.
The lever that matters most: light
Light is the dominant signal your circadian clock uses to set itself, which makes timed light exposure the most powerful tool you have. The principle is to seek bright light when you want to feel alert and shift toward local time, and to avoid it when you want your clock to move the other way. The direction depends on which way you flew: after an eastward flight, get morning sun and avoid bright light late at night; after a westward flight, soak up evening light and avoid bright morning light until your clock has shifted.
Getting this right is more effective than most travelers realize — and getting it backward can deepen the jet lag rather than ease it.
Jet lag is worse after eastward than westward travel, and worse the more time zones you cross. That asymmetry is why the same light or melatonin advice flips depending on your direction of travel.
Melatonin: what the evidence supports
The Cochrane review by Herxheimer and Petrie (“Melatonin for the prevention and treatment of jet lag”) examined ten trials; eight of them showed melatonin reduced jet lag from flights crossing five or more time zones, with the benefit greater for eastward travel. The specifics worth knowing:
| Factor | What the review found |
|---|---|
| Effective dose | 0.5–5 mg are similarly effective; people sleep better on 5 mg |
| Above 5 mg | No more effective |
| Slow-release 2 mg | Relatively ineffective — a short, higher peak works better |
| Best candidates | Flights ≥5 time zones, especially eastward |
A practical caution: taken at the wrong time — early in the local day — melatonin can cause daytime sleepiness and actually delay adjustment.
Other tactics with reasonable support
- Shifting your schedule a little before departure, where feasible.
- Strategic caffeine for daytime alertness — and avoiding it close to local bedtime.
The takeaway
Jet lag is fundamentally a clock-alignment problem, and light is the master switch for fixing it. Use timed light correctly for your direction of travel, and consider 0.5–5 mg of fast-release melatonin at the right local hour — best supported for eastward trips across five or more time zones. The tactics are well-founded but direction-dependent, so the one mistake to avoid is applying them backward.