Get a personalized day-by-day jet lag recovery plan — with exact light exposure, melatonin, and sleep timing for every day before and after your trip.
Based on Eastman & Burgess light-shifting protocol
Jet lag occurs when your internal circadian clock — governed by the suprachiasmatic nucleus (SCN) in your brain — is misaligned with the local day-night cycle at your destination. The clock resets primarily through light exposure, which suppresses or triggers melatonin production and directly shifts the phase of your circadian rhythm.
This calculator implements the Eastman & Burgess (2009) protocol, which uses timed light exposure and melatonin to shift the clock at approximately 1–2 hours per day. The two key levers are:
For shifts greater than 8 hours, it is sometimes faster to shift in the opposite direction (e.g., a 10h eastward shift is equivalent to a 14h westward shift, so going "west" may be easier). The calculator flags this when relevant.
Jet lag typically lasts 1 day per time zone crossed when traveling east, and about 0.75 days per time zone when traveling west. A 6-hour eastward flight (e.g., New York to London) may take 4–6 days to fully recover from; the same westward trip might take only 3–5 days.
The difference comes down to the natural drift of your circadian clock. Your body's internal clock runs slightly longer than 24 hours — roughly 24.2 hours — which makes it easier to delay (west travel) than to advance (east travel). Symptoms like daytime fatigue, difficulty sleeping, poor concentration, and digestive disruption typically peak on days 1–2 and fade by day 4–7 depending on the shift size.
The most effective strategies to avoid jet lag combine pre-trip adjustment, light exposure timing, and melatonin. Start shifting your sleep schedule 2–3 days before departure: go to bed 1–1.5 hours earlier each night for eastward travel, or later for westward travel.
Once you arrive, bright morning light is the most powerful tool for eastward adjustment — it advances your circadian clock. Avoid bright light in the evening when traveling east. For westward travel, reverse this: seek evening light and avoid early morning light. Taking 0.5 mg of melatonin 5 hours before your new target bedtime also accelerates clock shifting. Stay hydrated, avoid alcohol on the flight, and spend time outdoors on arrival days to anchor your new schedule.
Yes — eastward travel is consistently harder than westward travel. Research shows that adaptation to eastward shifts takes roughly 33% longer than equivalent westward shifts. A 6-hour eastward journey may need 6 days to resolve; the same westward trip only 4–5 days.
The reason is biological: your internal clock naturally runs a bit longer than 24 hours, making it easier to extend your day (delay your schedule, i.e., go to bed later — what westward travel requires) than to shorten it (advance your schedule, i.e., go to bed earlier — what eastward travel requires). This is also why night owls tend to suffer more from eastward jet lag: their clocks are already running late and find advancing even harder.
Yes, melatonin is one of the best-supported interventions for jet lag, particularly for eastward travel. The key is dosage and timing: research by Eastman & Burgess (2009) recommends 0.5 mg — a low dose — taken 5 hours before your desired new bedtime at the destination when traveling east, or at wake time when traveling west.
Higher doses (3–10 mg) are widely sold but are not more effective and can cause next-day grogginess. The low 0.5 mg dose acts as a circadian signal rather than a sedative, which is why it works better. Melatonin shifts the clock; it does not knock you out. Start taking it on the day of travel and continue for 3–4 days at destination for best results.
A jet lag recovery plan is a day-by-day schedule specifying exactly when to seek bright light, avoid light, take melatonin, and target sleep — tailored to your direction of travel and time zone shift. Rather than relying on willpower or "just pushing through," a structured plan works with your circadian biology.
The plan this calculator generates is based on the Eastman & Burgess (2009) protocol. For eastward travel, it advances your sleep window and light exposure by roughly 1.5 hours per day. For westward travel, it delays your schedule by the same amount each day. Pre-trip adjustment days (when you have time before departure) are included to give you a head start, so you arrive already partially adapted to the new time zone.
This time zone adjustment calculator implements the light-dark cycle shifting method from Eastman & Burgess (2009). You input your home and destination time zones, your habitual sleep schedule, and how many days you have before travel.
The calculator determines your direction (east or west), computes the total clock shift needed, and generates a day-by-day plan. Each day's card shows a light exposure window (when to be in bright sunlight or use a light box), a light avoidance window (when to wear sunglasses or stay indoors), a melatonin time (0.5 mg at the calculated phase-shifting moment), and a target sleep window that shifts 1.5 hours per day toward your destination schedule. Pre-trip days shift your clock before you even board the plane.