Jet lag is one of the rare corners of the supplement world with a genuinely clear answer. One supplement, melatonin, actually works, backed by strong evidence, and almost everything else marketed for travel is weak or unproven for jet lag specifically. The other half of the answer is not a supplement at all: getting your light exposure right does as much heavy lifting as any pill. This guide explains why jet lag happens, exactly how to use melatonin (dose and timing both matter), where light and caffeine fit, and which "jet lag formulas" are not worth your money.
The short version
- Melatonin is the standout, the one supplement with strong evidence for reducing jet lag.
- Use 0.5 to 5 mg at destination bedtime; low doses work as well as high ones, and timing matters most.
- Light exposure is an equally powerful, proven lever, and it is free.
- Jet lag is usually worse traveling east, and eases roughly a day per time zone.
- Magnesium, valerian, and "jet lag formulas" are weak or unproven for the clock mismatch itself.
What jet lag actually is
Jet lag happens when your internal body clock, your circadian rhythm, is still set to where you came from while the world around you runs on destination time after crossing several time zones. The result is fatigue, broken sleep, mental fogginess, and sometimes stomach upset, until your clock gradually catches up (roughly a day per time zone). It is typically worse traveling east, because flying east forces you to fall asleep earlier than your body wants, which is harder than staying up later going west. Jet lag is usually self-limited, but the point of any intervention is to speed the reset, and only two things reliably do that: melatonin and light.
What actually has evidence
| Option | Evidence | What it does | How to use |
|---|---|---|---|
| Melatonin | Strong | Shifts the body clock; clearly reduces jet lag in trials | 0.5-5 mg at destination bedtime |
| Light timing | Strong (not a supplement) | The other proven lever to reset the clock | Morning light going east |
| Strategic caffeine | Limited-Moderate | Improves daytime alertness; does not reset the clock | Daytime only |
| Magnesium / L-theanine | Limited | Sleep-adjacent; may help you sleep, not re-time you | Evening, as a sleep aid |
| Valerian / chamomile | Limited | Gentle sleep support; no jet-lag trials | Evening comfort measure |
| Vitamin B12 | No good evidence | Marketed for travel "energy"; unproven for jet lag | Not recommended for this |
Melatonin, the standout
If you take one thing from this guide, it is how to use melatonin. A Cochrane review concluded it is remarkably effective at preventing and reducing jet lag, with the large majority of trials showing clear benefit, especially when crossing five or more time zones and traveling east. The practical rules:
- Dose: 0.5 to 5 mg. Low doses work about as well as high ones, so start low; more is not better and just risks grogginess.
- Timing is everything: take it at your destination bedtime, starting the night you arrive, for a few nights. Taken at the wrong hour, melatonin can nudge your clock the wrong way.
- Quality matters: melatonin content in products is notoriously variable, so choosing a well-tested one helps; see our melatonin guide.
Light timing, the free lever
Melatonin's equal partner is light, and it costs nothing. Bright light at the right hour shifts your body clock, and getting the timing wrong can actually worsen jet lag. The simple version: traveling east, seek bright light in the morning and avoid it late at night, which helps advance your clock to the new, earlier schedule. Traveling west, do the reverse, getting light later in the day to delay your clock. Pairing well-timed light with well-timed melatonin is far more effective than either alone, and it is the core of every evidence-based jet lag protocol.
Caffeine and the rest
- Strategic caffeine. A review of trials found caffeine improves daytime alertness during jet lag, which helps you function, but it does not reset your clock and can wreck that night's sleep if taken too late. Use it in the daytime only, and stop well before your target bedtime.
- Sleep-adjacent supplements. Magnesium, L-theanine, valerian, and chamomile may help you fall asleep at your destination, but there is no good evidence they re-time your body clock the way melatonin and light do. They are comfort aids, not circadian fixes; our sleep supplement guide covers them in depth.
- Vitamin B12 is often marketed for travel energy, but controlled studies do not support it for jet lag.
What to skip or be skeptical of
- Generic "jet lag formulas." Any benefit usually rides on the melatonin they contain; the extra "clock" herbs stacked around it lack jet-lag evidence, so you are often paying a premium for plain melatonin.
- Homeopathic "No-Jet-Lag" products. Regulators note these have not been shown effective, and there is no good evidence behind them.
Cautions and when to ask
Jet lag is usually harmless and self-correcting, but a few points are worth heeding. Melatonin causes drowsiness and can interact with blood thinners, sedatives, and blood-pressure and diabetes medications, so do not drive or operate machinery right after taking it, and check with a pharmacist about interactions. See a clinician if insomnia or fogginess persists well beyond the normal adjustment window, or if you have a condition affected by sleep or by sedating supplements. For frequent travelers, building a simple melatonin-plus-light routine is far more effective than chasing novelty products.
Frequently asked questions
Does melatonin help jet lag?
Yes, it is the best-evidenced supplement for jet lag. A Cochrane review found melatonin remarkably effective, with most trials showing clearly reduced jet-lag symptoms when it was taken close to destination bedtime, especially after crossing several time zones. Among supplements marketed for travel, melatonin is the one that genuinely works.
How much melatonin should I take for jet lag, and when?
Typically 0.5 to 5 mg taken at your destination bedtime, starting the night you arrive, for a few nights. Low doses work about as well as high ones with fewer side effects, so more is not better. Timing matters more than dose: taken at the wrong time, melatonin can shift your clock the wrong way.
Which direction makes jet lag worse?
Eastward travel is usually worse. Flying east forces you to fall asleep earlier than your body wants, which is harder than delaying your clock, so eastbound trips tend to hit harder and take longer to adjust to. Westward travel, where you stay up later, is generally easier to handle.
Is more melatonin better for jet lag?
No. Higher doses are not clearly more effective for jet lag and are more likely to leave you groggy the next day. The low end of the range works about as well, and getting the timing right, at destination bedtime, matters far more than the size of the dose.
Do magnesium or valerian fix jet lag?
Not specifically. Magnesium, valerian, L-theanine, and chamomile are sleep-adjacent and may help you fall asleep at your destination, but there is no good evidence they re-time your body clock the way melatonin and properly timed light do. They can be a comfort aid, not a fix for the circadian mismatch itself.
Can I just use caffeine to power through jet lag?
Caffeine can genuinely boost daytime alertness during jet lag, which helps you function, but it does not reset your body clock and can wreck that night's sleep if taken too late. Use it strategically in the daytime only, and avoid it within roughly six to eight hours of your target bedtime.
The bottom line
Jet lag has a refreshingly clear playbook. Melatonin is the one supplement that genuinely works, used at a low 0.5 to 5 mg dose at your destination bedtime, and its power roughly doubles when paired with well-timed light (morning light going east). Caffeine helps you push through the day but does not reset anything, sleep-adjacent supplements are comfort aids rather than circadian fixes, and generic "jet lag formulas" mostly just charge you extra for the melatonin inside. Build a simple melatonin-and-light routine, respect the timing, and you will adjust faster than any novelty travel pill can promise.