Health & medical
How to beat jet lag: what science actually says works
By the TSA Wait Times team · Updated · Published June 2026
Jet lag is your circadian rhythm being out of sync with the destination clock. Your body adjusts at roughly 1 time zone per day — so a 6-hour jump takes about 6 days to fully resolve. You cannot eliminate jet lag, but you can cut recovery time in half with the right moves.
East vs west: why direction matters
Flying east (e.g., New York to London)
Harder. Your body has to advance its clock — wake up and sleep earlier than it wants to. Most people find this more difficult.
Flying west (e.g., New York to LA, or California to Japan going west)
Easier. Your body has to delay its clock — stay up later than normal. The natural human circadian rhythm is slightly longer than 24 hours, so delaying feels more natural.
Rule of thumb
Expect about 1 day of adjustment per time zone crossed, slightly worse going east.
Before you fly
- Shift early (eastbound) or late (westbound). If flying east, start going to bed 30–60 minutes earlier for 2–3 nights before departure. If flying west, shift later by the same increment.
- Arrive rested. Sleep debt makes jet lag significantly worse. Sleep-deprived travelers experience more severe and longer-lasting symptoms — do not start the trip already behind.
- Hydrate the day before. Start hydrating the day before and on travel day. Dehydration amplifies fatigue and makes jet lag symptoms harder to distinguish from simple tiredness.
During the flight
- Set your watch to destination time. Mentally commit to the new time zone immediately. Eat and sleep according to when you would at the destination, not the origin.
- Sleep strategically. If it is nighttime at your destination, sleep. If it is daytime, stay awake. Sleeping at the wrong local time makes adjustment harder, not easier.
- No alcohol. Alcohol disrupts sleep architecture — even one drink affects sleep quality significantly at altitude. The sedation feeling is not real sleep.
- Melatonin on the plane (eastbound only). If you need to sleep on the plane and it aligns with destination night, take 0.5 mg melatonin 30 minutes before target sleep time. Research supports this dose.
At the destination: light exposure is the master clock signal
Light is the most powerful jet lag tool. Your circadian clock is set primarily by light exposure to your retinas — more than any supplement or behavior change. Use it directionally.
Flew east
- Get bright outdoor light in the morning at destination — advances your clock forward
- Avoid bright light in the evening for the first 2–3 days
- Walk outside after breakfast — even 15–20 minutes of daylight is enough
Flew west
- Get bright light in the late afternoon / evening — delays your clock, exactly what you need
- Stay up as late as you can on your first night
- Do not nap early in the afternoon
Light therapy boxes
If traveling in winter or to locations with limited daylight, a 10,000 lux light therapy box (15–30 minutes in the morning) substitutes effectively for natural sunlight and is supported by circadian research.
Melatonin: how to use it correctly
- Dose: 0.5 mg. Most OTC melatonin is sold in 3–10 mg doses — far more than needed. Higher doses do not increase effectiveness but do increase next-day grogginess. Cut a standard 5 mg tablet or buy 0.5 mg formulations specifically.
- Timing: at destination bedtime. Take it at the clock time you want to be asleep — not when you feel sleepy. Continue for the first 3–4 nights after arrival.
- Flying east:Start taking melatonin at 10 pm destination time beginning the day of arrival. Continue for 3–4 nights.
- Flying west: Generally not needed — melatonin is less effective for westward travel where the goal is clock delay, not advance.
- Buy it before you go. Melatonin is not available OTC in many countries — it requires a prescription in the UK, for example. Stock up domestically before departure.
Caffeine strategy
Caffeine can help you stay alert when you need to, but it blocks melatonin and disrupts sleep if taken too late in the destination day.
- Use caffeine in the morning (destination time) to push through the first day and signal wakefulness to your circadian system.
- Stop caffeine by 2 pm destination time for the first few days — even if you normally drink coffee later at home.
- Half-life is 5–6 hours. A 3 pm coffee is still affecting your ability to fall asleep at 9 pm. This math matters more when your circadian system is already under stress.
Napping: yes or no
Brief nap: OK
20 minutes, before 3 pm destination time. Reduces fatigue without disrupting nighttime sleep. Set an alarm — oversleeping is the only risk.
Long nap: avoid
90+ minutes, or any nap after 3 pm, makes adjustment significantly harder. If you are dangerously exhausted on arrival, a 90-minute nap is better than a safety risk — but treat it as a one-time exception, not a strategy.
Apps and tools that actually help
- Timeshifter (app, free/paid) — created by circadian researcher Dr. Steven Lockley. Generates a personalized jet lag plan based on your specific flights, covering light exposure, melatonin, caffeine, and sleep timing. Genuinely useful for multi-timezone travel.
- Jet Lag Rooster (free web tool) — simpler calculator for light/dark exposure timing. No app required, no account needed.
The west-1 travel hack
If flying west and your destination is only one time zone behind, the body often experiences no jet lag at all — a single time zone west is within normal circadian variation. No intervention needed.
For business travelers: the short trip problem
For trips under 3 days across many time zones, it can be rational to not adjust to the destination clock at all. Sleep on home time, and schedule your most important meetings during hours when you are naturally alert. This only works for very short trips.
For trips of 4+ days: adjust fully as described above. The short-trip strategy becomes counterproductive once you need to function on local time for more than a couple of days.
Frequently asked questions
How long does jet lag last?
Roughly 1 day per time zone crossed. A 6-hour jet lag typically resolves in 4–7 days without intervention — faster (2–4 days) with proper light exposure and melatonin.
Does melatonin actually help jet lag?
Yes — multiple randomized controlled trials show melatonin at 0.5–5mg (lower doses equally effective) taken at destination bedtime reduces jet lag symptoms. The 0.5mg dose is as effective as higher doses with fewer side effects.
Is eastward or westward jet lag worse?
Eastward travel causes worse jet lag for most people — advancing the clock is harder than delaying it. Flying from the US to Europe typically produces stronger symptoms than flying from Europe to the US.
What helps jet lag most?
Morning sunlight at your destination (if flying east), 0.5mg melatonin at destination bedtime, no alcohol on the flight, and strategic caffeine use. Light is the most powerful intervention.
Related guides
- Red-eye flight tips: how to actually sleep on the plane — seat selection, gear, melatonin timing, and how to land without feeling destroyed
- International travel checklist — passport, visa, Global Entry, and what to do 48 hours before departure
Know your Leave-By Time before you head to the airport
International flights require extra buffer time — customs, additional security screening, and long terminal walks all add up. Use the Leave-By Time calculator to factor in live TSA wait times, your drive, and check-in cutoffs into one exact time to leave home.
Calculate your Leave-By Time →Verified as of . Sources: Sleep Foundation, NIH / PMC — Melatonin for Jet Lag, Wu Tsai Human Performance Alliance.