Jet lag is what happens when your internal body clock is still running on home time while the world around you has moved on. You’re wide awake at 3 a.m., foggy at noon, and your gut and appetite are just as confused as your head. The good news: the most effective jet lag remedies aren’t exotic. They come down to timing two things correctly — light and, optionally, melatonin — based on which direction you flew.
This guide gives you the rules, the doses, and a sample plan you can actually follow.
Quick answer
- Recovery takes roughly one day per time zone crossed, with eastward travel harder than westward.1
- Light is your most powerful tool. Morning light pulls your clock earlier; evening light pushes it later.
- Melatonin helps, especially for five or more time zones eastward. Effective doses run 0.5–5 mg taken near destination bedtime.2
- Direction is everything. Get the timing backward and you’ll make jet lag worse, not better.
Why jet lag happens
Your body runs on a roughly 24-hour internal clock, set largely by light. Cross several time zones in a few hours and that clock is suddenly out of sync with local day and night. Until it catches up, your sleep, alertness, digestion, and mood are all offset.
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Explore new cuisinesIt re-syncs slowly — about one time zone per day. Flying from London to Tokyo (nine time zones east) can mean the better part of a week before you feel normal, while a one- or two-zone hop barely registers.1 Eastward is harder because you have to advance your clock (go to bed earlier than your body wants), and the human clock naturally runs slightly long, so delaying is easier than advancing.
The direction rules
This is the core of beating jet lag. What you do depends entirely on which way you flew.
| Direction | Your goal | Seek light | Avoid light |
|---|---|---|---|
| Eastward (e.g. US → Europe) | Advance clock (sleep earlier) | Morning, at destination | Late evening |
| Westward (e.g. Europe → US) | Delay clock (sleep later) | Evening, at destination | Early morning |
Light is the strongest cue your circadian system responds to, and getting (or blocking) it at the right time is what actually moves your clock.3 Sunglasses and a dim phone are useful tools for avoiding light when you need to.
A practical shortcut: after an eastward flight, get outside in the morning sun and protect yourself from bright light late at night. After a westward flight, soak up evening light and avoid bright morning light until your clock has shifted.
How to dose melatonin
Melatonin is the hormone your brain releases as darkness falls; it’s a timing signal, not a sedative. Taken correctly, it’s genuinely effective for jet lag. A Cochrane review of ten trials found melatonin taken near destination bedtime reduced jet lag from flights crossing five or more time zones, with a number-needed-to-treat of just 2 — meaning it helped about every other traveler.2
Key points from that evidence:
- Dose: anywhere from 0.5 mg to 5 mg works. Higher doses (5 mg) help you fall asleep faster and sleep a bit better, but doses above 5 mg aren’t more effective.2
- Timing: take it close to your target bedtime at the destination (roughly 10 p.m. to midnight local time).
- Direction: the benefit is greatest for eastward travel across many time zones, and smaller for westward flights.
- Timing matters more than dose: take it at the wrong time — early in your destination’s day — and it can cause daytime sleepiness and actually delay your adjustment.2
Start with a low dose (0.5–1 mg) and only go higher if you need more help falling asleep. For the broader picture on uses, safety, and timing, see our melatonin guide.
Caveats worth knowing: melatonin is generally safe for short-term use, but case reports flag caution for people with epilepsy and those taking warfarin.2 Talk to your doctor first if either applies to you, or if you’re pregnant.
Suggested read: Blue Light and Sleep: How Light Affects Melatonin
A sample plan: flying east across 6+ time zones
- 2–3 nights before: shift your bedtime about an hour earlier each night.
- On the flight: if it’s overnight at the destination, try to sleep. Skip alcohol — it fragments sleep and dehydrates you.
- First evening at destination: take 0.5–3 mg melatonin near local bedtime.
- Each morning: get outside into bright light as early as you reasonably can.
- Late evening: keep lights dim, screens down; wear sunglasses if you’re out after dark.
- Repeat the melatonin-plus-morning-light pattern for a few nights until you’ve adjusted.
For westward trips, flip it: chase evening light, avoid early-morning light, and keep yourself up a little later rather than forcing an early bedtime.
What else helps (and what doesn’t)
Worth doing:
- Set your watch to destination time the moment you board, and eat and sleep on that schedule.
- Stay hydrated — dry cabins make the fog worse. See hydration on planes.
- Short naps (20–30 min) can take the edge off without wrecking your nighttime sleep.
Overrated:
- “Jet lag diets” with rigid fasting-feeding cycles — the evidence is thin and they’re hard to follow.
- Sleeping pills — they may help you sleep but don’t reset your clock, and they carry their own downsides.
- Megadosing supplements — none reset your circadian clock the way light does.
Strong general sleep habits make every part of this easier — see tips to sleep better. For the bigger travel-wellness picture, our travel health tips pillar pulls it all together.
Suggested read: Red Light at Night: Why It's Gentler on Sleep
How long will it really last?
Set realistic expectations and you’ll be less frustrated. Plan for roughly one day of recovery per time zone crossed, so a six-zone eastward trip means about five to six days before you’re fully back to normal — though you’ll feel meaningfully better well before that if you time light and melatonin correctly.1
Symptoms usually peak in the first two or three days and then ease. Beyond the obvious sleep trouble, jet lag commonly brings daytime fatigue, trouble concentrating, irritability, and a disrupted gut — your digestion runs on the same internal clock, which is why constipation and jet lag so often travel together. If your stomach acts up, our travel constipation guide covers the fix.
A few situations make jet lag worse: very short trips (your clock barely starts adjusting before you head home), back-to-back long-hauls, and arriving already sleep-deprived. For a two- or three-day trip across many time zones, some people deliberately stay on home time rather than fight a full reset — it depends on whether your daytime commitments can flex.
Who should be cautious with melatonin
Melatonin is low-risk for short-term use in healthy adults, but it isn’t for everyone. Skip it or check with a doctor first if you:
- Take warfarin or other anticoagulants — a possible interaction has been flagged.2
- Have epilepsy — case reports raise concern.2
- Are pregnant or breastfeeding, since safety data is limited.
- Drive or operate machinery soon after — a badly timed dose can leave you drowsy when you need to be alert.2
Quality control on over-the-counter melatonin is inconsistent between products, so buy from a reputable brand and start at the low end of the dose range.
Bottom line
Jet lag follows predictable rules: expect about a day of recovery per time zone, with eastward trips the rough ones. Time bright light correctly — morning light going east, evening light going west — because light is what actually shifts your clock. Add melatonin (0.5–5 mg near destination bedtime) for longer eastward flights, and respect the timing, since a badly timed dose backfires. Skip the gimmicks. Get those two levers right and you’ll feel like yourself days sooner.
Herxheimer A. Jet lag. BMJ Clin Evid. 2014;2014:2303. PubMed ↩︎ ↩︎ ↩︎
Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520. PubMed | DOI ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Woelders T, Beersma DGM, Gordijn MCM, Hut RA, Wams EJ. Daily Light Exposure Patterns Reveal Phase and Period of the Human Circadian Clock. J Biol Rhythms. 2017;32(3):274-286. PubMed | DOI ↩︎
