Jet Lag Planner

Flight Map

Day-by-Day Recovery Schedule

Time Zones Crossed → Recovery Days

Pair with Sleep Cycle Calculator to time first-night bedtime at destination.

The Eastman-Burgess Recovery Formula

Nothing saved yet. Tap "Save Snapshot" to remember the last six itineraries.

How to Plan a Jet-Lag Recovery

1. Pick departure and arrival airports from the selectors. The IATA codes (BOM, SFO, LHR, JFK) match major hubs.
2. Read the zone shift and direction. Eastward is harder - allow more recovery days.
3. Walk down the recovery cards day by day, scheduling outdoor bright light in the right window and blacking out the dark window.
4. Take 0.3 mg melatonin (the small dose, not the 3 mg gummies) at the time the card lists relative to destination local time.
5. Save the snapshot, then check the live clocks on flight day. The browser uses IANA TZDB so DST is automatic.

The Science Behind Jet Lag

In 2026, an Indian executive boarding a non-stop Mumbai-to-San Francisco flight crosses thirteen and a half hours of time zones in a sixteen-hour journey. Arriving for a Monday morning kickoff is biologically equivalent to working at midnight from a Mumbai clock - which is exactly why so many do that meeting from a fog. Jet Lag Planner translates the time-zone shift into a realistic recovery schedule with timed light, dark, melatonin, and caffeine windows so the second day at destination is workable.

The biological clock that drives jet lag is the suprachiasmatic nucleus (SCN), the hypothalamic pacemaker identified by Robert Moore and Friedrich Stephan in 1972. It runs an endogenous period slightly longer than 24 hours (24.18 h on average, Czeisler et al., Science, 1999) and is entrained daily by retinal light. The SCN can shift the body's master rhythm by at most one to one-and-a-half time zones per day under ideal conditions; cross more than that in a single hop and the system fragments into 'internal desynchrony.'

Charles Czeisler at Harvard and Anna Wirz-Justice in Basel laid down the modern light-therapy rules for jet lag in the 1980s and 1990s. The phase response curve (PRC) for light - mapped originally by Patricia Lakin-Thomas and refined by Eastman and Burgess at Rush University - shows that bright light in the late biological evening delays the clock, light in the early biological morning advances it. The NIH National Heart, Lung, and Blood Institute's 2016 jet-lag guidance and the American Academy of Sleep Medicine's 2015 clinical practice guideline both endorse light, melatonin, and timed sleep as the primary countermeasures.

The phase response curve for melatonin is opposite to that of light. Alfred Lewy at Oregon Health Sciences University showed in 1992 that 0.3 mg to 0.5 mg of melatonin, taken five to six hours before habitual sleep, advances DLMO (dim-light melatonin onset) by about one hour. Larger doses (3 mg, 5 mg) are no more effective and can produce next-day grogginess. The PRC inverts: morning melatonin delays, evening melatonin advances. Jet Lag Planner schedules the dose against the destination clock, not the home clock.

Eastward travel is biologically harder than westward because the body's natural drift is to delay (the free-running circadian period is longer than 24 hours). A westbound 6-hour shift fits the body's drift and resolves in roughly three days. An eastbound 6-hour shift fights the drift and takes five to six days, sometimes seven. The literature speaks of an asymmetry coefficient of about 0.6: eastward = westward × 1.6.

The IATA Medical Manual and the ICAO Doc 9966 fatigue-risk management standard both reference jet lag as a major safety variable for crews. Aircraft like the Boeing 787 Dreamliner and the Airbus A350-1000 use cabin-altitude lighting that simulates dawn and dusk on transmeridian flights to nudge the body's clock. Long-haul cabin crews use Fatigue Risk Management Systems (FRMS) that compute exactly the same kind of recovery curve that Jet Lag Planner exposes to the public.

Modern timezone software, including the live arrival/departure clocks on this page, draws on the IANA Time Zone Database (TZDB), founded by Arthur David Olson at NIH in 1986 and now maintained collaboratively at iana.org/time-zones. Identifiers like Europe/London, America/New_York, Asia/Kolkata, Asia/Tokyo, and Australia/Sydney encode every DST rule change going back to 1880, so the directional shift this tool computes is always accurate against the current calendar.