Meridian jet lag planner

Science-based · Free · No sign-up

Land on local time.

A personal jet lag plan that tells you exactly when to sleep, when to find bright light and when to hide from it, plus melatonin and caffeine timing. It starts a few days before you fly and runs until your body clock catches up.

  • Light windows checked against real sunrise & sunset
  • In-flight sleep plan
  • Be sharp for a meeting, race or wedding
  • Return-trip plan included

Plan your trip

Route
Outbound flight

Your usual sleep at home, on a normal night
Coming back? optional; improves the strategy and adds a return plan
Days to prepare before you fly

Each prep day moves your sleep about an hour toward the destination.

Your goal
Include

How it works

Your body clock moves slowly. Light moves it.

1 · About 1–1.5 hours a day

Your body clock adjusts gradually. The planner uses the CDC's average rates: about 1 hour a day when shifting earlier (eastward) and 1.5 hours a day when shifting later (westward)[1]. Estimates vary; the AASM's patient guide uses about one day per time zone[4], so treat "adjusted by" as a best case.

2 · Timing is everything

Your body temperature bottoms out about 2–4 hours before your usual wake time; the planner uses 3 hours[1][6]. Bright light in the hours after that low point moves your clock earlier. Light in the hours before it moves your clock later. Get it the wrong way round and you adjust in the wrong direction.

Light before the temperature low point delays the clock; light after it advances the clock Light here → clock later Light here → clock earlier body temperature low (≈ wake − 3 h)

3 · Big eastward trips: the rule can flip

After flying 8 or more zones east, your body's low point first lands in the local morning, so morning light would push your clock the wrong way[3]. The planner still shifts you earlier, but has you avoid early-morning light at first and get light later in the day, moving the windows earlier each day. If 9+ hours would still need shifting when you land (for example with no prep days), the clock tends to drift later instead, so the plan goes that way[6]. Chicago → Tokyo is simply a 10-hour later shift (Tokyo is 14 h ahead), so it gets evening light.

4 · Short trips: stay on home time

For stays of 2 days or less, keep your home sleep, meal and activity times as closely as you can instead of adapting[1][2]. "Meet halfway" is offered as an extra option but isn't part of CDC or AASM guidance.

The protocol

Four steps, in plain language

  1. 1

    Plan ahead 2–3 days before

    • Shift bedtime and wake time about 1 hour a day toward your destination[1][2].
    • Eastbound: bed and wake 1 hour earlier each day, with bright light in the morning.
    • Westbound: bed and wake 1 hour later each day, with bright light in the evening.
    • Short trip (2 days or less) across many zones? Stay on your home schedule.
  2. 2

    Travel smart

    During the flight

    • Set your watch to destination time as soon as you board; eat and sleep on it[1].
    • Drink water. Go easy on alcohol and caffeine; both disrupt sleep.
    • Avoid antihistamine sleep aids and long-acting sedatives[1].

    After you land

    • Get outside for natural light (see step 3 for timing).
    • Keep naps to 20–30 minutes[1].
    • Stay awake until your new local bedtime.
    • Move your body during local daytime, ideally outdoors[4].
    • Caffeine is fine for daytime alertness; stop 6 hours before bed[1].
  3. 3

    Time your light

    • Flying east (e.g. US → Europe): bright light in the morning; avoid it in the evening[1].
    • Flying west (e.g. Europe → US): bright light in the evening; avoid it in the morning[1].
    • 8+ zones: the rule can flip. Your plan above gives exact windows[3][6].
  4. 4

    Melatonin optional; talk to your doctor

    • Flying east across 5+ time zones: a low dose 30–60 minutes before your destination bedtime, from the night you arrive, for up to about 5 nights[5]. 0.5–1 mg is usually enough; don't take more than 5 mg[1].
    • Flying west: generally not needed. Taken at bedtime it can work against shifting later[3]; light timing does the work instead.
    • Melatonin is sold as a supplement and isn't FDA-regulated, so what's in the bottle can differ from the label[1].

Questions

Good to know

Does this follow CDC and AASM guidance?

Yes. The pre-trip shift, adjustment rates, light timing, nap length, caffeine, short-trip and melatonin advice follow the CDC Yellow Book[1] and the American Academy of Sleep Medicine's jet lag recommendations[2][3][4], with details from the research listed under Sources. "Meet halfway" and the event alertness estimate are extra features that aren't part of that guidance.

What counts as "bright light"?

Outdoor daylight is best. Even an overcast day is many times brighter than indoor lighting. If a light window falls in the dark, use the brightest indoor light you can, or a light box if your doctor agrees. The plan tells you when that's the case.

How do I "avoid" light?

Stay indoors with dim, warm lighting. Outside, wear dark sunglasses, and turn down screen brightness. On the plane, use the window shade and an eye mask.

Why no melatonin for westward trips or short hops?

The evidence for melatonin is strongest for eastward flights across 5 or more time zones, taken at bedtime at your destination[5]. After flying west, a bedtime dose falls in your body's late night and can work against the later shift you need[3]. Taking it in the middle of the night to shift later is untested in jet lag studies[6], so the plan relies on evening light and dim mornings instead. If you keep waking too early after a westward trip, ask your doctor what might help.

Who should be careful with melatonin or light boxes?

Talk to your doctor first[4]. Melatonin is generally not advised during pregnancy or breastfeeding, for children, with other medicines unless supervised, or before driving until you know how it affects you. Bright light boxes need care with eye disease, light-sensitising medicines, migraines or bipolar disorder[6].

What about sleeping pills?

Short-acting prescription sleep aids are an option to discuss with your doctor for jet lag insomnia[1][2]. Avoid antihistamine sleep aids and long-acting sedatives, especially on the plane[1].

Is my data stored anywhere?

No. Everything is calculated in your browser. Your last trip is remembered on this device only (use "New plan" to clear it), and the share link holds your trip details in the URL itself.

Does it work offline?

Yes. After your first visit the planner is cached, so you can open your plan on the plane. On a phone, use "Add to Home Screen" to install it like an app.

How accurate is this?

It uses well-established rules about how light shifts the body clock, with average rates. People vary, and field evidence for timed light is still limited[3], so treat the times as a guide and not to the minute. If you feel you're adjusting faster or slower, trust your body.

Sources

References

  1. Riedy SM, Williams SG. Jet lag disorder. In: CDC Yellow Book: Health Information for International Travel. Centers for Disease Control and Prevention; reviewed 2025. cdc.gov
  2. Morgenthaler TI, Lee-Chiong T, Alessi C, et al. Practice parameters for the clinical evaluation and treatment of circadian rhythm sleep disorders. An American Academy of Sleep Medicine report. Sleep. 2007;30(11):1445–1459. aasm.org (Still the AASM's jet lag guidance; the 2015 update did not cover jet lag.)
  3. Sack RL, Auckley D, Auger RR, et al. Circadian rhythm sleep disorders: Part I, basic principles, shift work and jet lag disorders. An American Academy of Sleep Medicine review. Sleep. 2007;30(11):1460–1483. aasm.org
  4. American Academy of Sleep Medicine. Jet lag. Sleep Education. sleepeducation.org
  5. Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520. cochrane.org
  6. Burgess HJ. Using bright light and melatonin to reduce jet lag. In: Perlis M, Aloia M, Kuhn B, eds. Behavioral Treatments for Sleep Disorders. Academic Press; 2011:151–157. doi.org
  7. Roach GD, Sargent C. Interventions to minimize jet lag after westward and eastward flight. Front Physiol. 2019;10:927. doi.org