Jet Lag Calculator

Science-backed recovery plan with light exposure schedule, melatonin timing & in-flight sleep window.

Flight Details

Jet Lag Analysis

Moderate
5-hour shift ➡ Eastward
MildModerateSignificantSevere
Body Clock
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⇨ +5h
Destination
--:--
TZ Shift
+5h
Recovery
5 days
Arrival (local)
--:--
Body Clock
--:--
Target Bedtime
--:--
Melatonin At
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Flight Duration
7h
Severity
Moderate
Alertness Recovery Timeline

🌞 Light Exposure Schedule

Based on circadian science: bright light at the right time is the most powerful way to reset your body clock. Yellow = seek light, blue = avoid light, ● = take melatonin.

Seek bright light
Avoid bright light
Melatonin (0.5–3mg)

💊 Melatonin Schedule

DayTake At (destination)DoseNotes

🌟 Personalised Recovery Protocol

📅 Day-by-Day Recovery Schedule

DayTarget BedWakeAlertnessFocus for Today

⇆ Eastward vs Westward Comparison

➡ Eastward
—
~1 day recovery per time zone
⬅ Westward (easier)
—
~0.75 days per time zone

✈ Pre-Flight Sleep Adjustment

Shift your sleep schedule before departure to arrive partially adapted. Start 3 days before your flight.

✈ In-Flight Sleep Window

Sleeping at the optimal time on the plane helps your body clock begin adjusting mid-flight.

Recommended sleep window
Stay awake

🌎 Arrival Day Schedule (Day 1)

Your personalised hour-by-hour plan for the first day at your destination.

Time (local)ActionWhy it helps

🏴 In-Flight Tips

🏦 Destination Recovery Tips

How to Use the Jet Lag Calculator

1

Select route

Choose a preset route or manually set your departure and destination time zones. Add your usual bedtime and chronotype for a personalised plan.

2

Check the analysis

See your severity rating, dual body-clock display, arrival time, and melatonin timing. The chart shows your predicted alertness recovery curve.

3

Follow the light schedule

The Recovery Plan tab shows a day-by-day light exposure schedule — the most scientifically proven way to reset your circadian rhythm faster.

4

Use the sleep scheduler

Pre-adjust your sleep before departure, plan your in-flight sleep window, and follow the Day 1 arrival schedule for the smoothest possible transition.

Jet Lag Formulas

Recovery (Eastward)= |TZ shift| × 1.0 × Age Factor
Recovery (Westward)= |TZ shift| × 0.75 × Age Factor
Melatonin Time= Target Bedtime − 90 min
Circadian Shift Rate= ~1.5 h per day (light-assisted)

Key Terms

Circadian Rhythm
The body's internal 24-hour clock regulating sleep, hormones, and metabolism. It takes time to shift to a new time zone.
Zeitgeber
Environmental cues — primarily light — that synchronize the circadian clock to local time. The most powerful tool for beating jet lag.
Melatonin
The "sleep hormone" produced by the pineal gland at night. Taking 0.5–3mg at the right time accelerates circadian resetting.
Phase Advance
Shifting the body clock earlier — required when traveling east. Harder for the body than phase delay.
Phase Delay
Shifting the body clock later — required when traveling west. More natural due to the clock's ~24.2h free-running period.
Chronotype
Your natural sleep preference (early bird / neutral / night owl). This affects the optimal timing of light exposure and melatonin.

Real-World Examples

NYC → London (+5h Eastward)

Recovery: ~5 days. Seek morning light 07:00–09:00 on Day 1. Take melatonin at 21:00 London time for 3 nights. Avoid screens after 20:00.

NYC → Tokyo (+14h Westward)

Recovery: ~8 days westward. Get evening light 18:00–20:00 on Day 1–3. Stay awake until 22:00 local. Melatonin less critical going west.

LA → London (+8h Eastward)

Recovery: ~8 days. Pre-adjust 3 days before by sleeping 1h earlier/day. In-flight: sleep last 4h. Day 1: outdoor walk by 08:00 local time.

The Science of Jet Lag Recovery

Jet lag occurs because your circadian rhythm is entrained to your home time zone while your destination operates on a different schedule. The suprachiasmatic nucleus (SCN) in your hypothalamus acts as a master clock, and it adjusts at roughly 1 hour per day eastward and 1.5 hours per day westward under normal conditions — meaning a 9-hour eastward shift takes about 9 days without intervention.

Light is the most powerful resetting tool. Bright light (1000+ lux) stimulates melanopsin-containing retinal ganglion cells that directly signal the SCN. For eastward travel, morning light at the destination phase-advances the clock. For westward travel, evening light phase-delays it. Strategic light avoidance is equally important — blue-light blocking glasses or blackout curtains during the avoidance window dramatically improve outcomes.

Melatonin (0.5–3mg taken at destination bedtime) works synergistically with light exposure. Research by Eastman and Burgess shows that combining light therapy with melatonin reduces adaptation time by 30–50% compared to either alone. Meal timing, exercise, and caffeine use are secondary zeitgebers — eating at destination meal times from Day 1 helps anchor the peripheral clocks in the liver and digestive system.

Frequently Asked Questions

Why is flying east worse than west for jet lag?

The human circadian clock naturally runs slightly longer than 24 hours (~24.2 hours), making it easier to extend the day (west) than compress it (east). Eastward travel requires a phase advance, which goes against the body's natural tendency.

How accurate is the recovery time estimate?

The formula (1 day/TZ hour east, 0.75 days/hour west × age factor) is based on published circadian research and represents the average without active countermeasures. With the light exposure schedule and melatonin, you can cut recovery time by 30–50%.

Does melatonin actually work for jet lag?

Yes — multiple randomized controlled trials confirm melatonin (0.5–3mg) taken at the target destination bedtime significantly reduces jet lag. Lower doses (0.5mg) are often as effective as higher doses with fewer side effects like morning grogginess.

What is the light exposure schedule based on?

The schedule is based on the Eastman-Burgess circadian photobiology research and the Czeisler lab's work at Harvard. Light at the right circadian phase can shift the clock by 1–2 hours per day. The algorithm calculates your current body-clock phase at arrival and schedules light to advance or delay it toward destination time at ~1.5h/day.

Should I sleep on the plane?

It depends on your arrival time. The in-flight sleep window in the Sleep Scheduler tab shows the optimal time to sleep based on your route and direction. For eastward flights, sleeping in the second half aligns you better with morning at the destination.

How can I adjust my sleep before departure?

For eastward travel, shift bedtime 1 hour earlier per day for 3–4 days before departure. For westward, delay it by 1 hour/day. The Pre-Flight Schedule in Tab 3 calculates the exact times based on your normal bedtime and flight direction.

Does caffeine help with jet lag?

Caffeine helps mask daytime sleepiness but doesn't accelerate circadian adaptation. Avoid it within 6 hours of target sleep time, as it delays melatonin production and can worsen recovery. Use it strategically in the morning at your destination.

Are older travelers more affected by jet lag?

Yes — circadian rhythms become less robust with age and melatonin production decreases. Travelers over 55 typically need 25–50% longer to recover, which is why the calculator applies a 1.3× age factor for the 56+ group.

What does chronotype affect in the calculation?

Chronotype (early bird / neutral / night owl) shifts your optimal bedtime and light exposure windows by ±1 hour. Early birds should start light exposure 1 hour earlier; night owls 1 hour later. This improves the precision of the melatonin schedule.

What foods help with jet lag recovery?

Protein-rich meals (eggs, meat, fish) increase alertness and support dopamine production. Carbohydrate-heavy meals promote sleep. Eat according to destination time from Day 1 — the digestive system has its own peripheral circadian clock that responds to meal timing.

Does exercise help reset the circadian clock?

Yes — moderate exercise (30-min walk) in the morning at your destination helps reset the clock via body temperature rhythms and cortisol. Avoid intense exercise within 3 hours of target bedtime as it raises core temperature and delays sleep onset.

What is the best arrival time for minimal jet lag?

Arriving at the destination's early evening (17:00–20:00 local) is ideal — you have time to stay awake until a normal bedtime, get outdoor light exposure, and sleep at the correct local time. Arriving at night is the worst scenario as it maximizes the time you must fight sleepiness.

Do sleeping pills help with jet lag?

Prescription sleep aids (zolpidem) can help achieve sleep at the right time on the first 1–2 nights, but they don't accelerate circadian adaptation. Use sparingly and avoid combining with melatonin. They work best for very long shifts (≥8h) where falling asleep at the right time is the main obstacle.

What is the Argonne Anti-Jet-Lag Diet?

A 4-day pre-travel protocol alternating "feast" days (high-protein breakfast, high-carb dinner) with "fast" days (light eating under 800 kcal). It manipulates liver glycogen and hormonal rhythms to pre-shift the internal clock. Studies show it can reduce adaptation time by up to 50% for major crossings.

How does hydration affect jet lag?

Airplane cabin humidity is only 10–20%, far below the comfortable 40–60% threshold. Dehydration amplifies fatigue, cognitive impairment, and headaches — all mimicking jet lag symptoms. Drink 250ml of water per hour of flight and avoid alcohol, which causes fragmented sleep and additional dehydration.

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