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
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TZ Shift
+5h
Recovery
5 days
Arrival (local)
--:--
Body Clock
--:--
Target Bedtime
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Melatonin At
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Flight Duration
7h
Severity
Moderate
Alertness Recovery Timeline
Chart: recovery chart.

🌞 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

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How to Use This 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.

Understanding Jet Lag

What Is Jet Lag?

Jet Lag is a fundamental concept that this calculator helps you understand and apply. Whether you're a beginner or experienced professional, having precise calculations at your fingertips saves time and reduces errors.

Why It Matters

Understanding jet lag helps you make informed decisions backed by data rather than guesswork. Small miscalculations can compound into significant errors, making accurate tools essential for planning and analysis.

How It Works

The Jet Lag Calculator — Recovery Time, Light Schedule & Melatonin Timing applies established formulas and methodologies to your specific inputs. Results update in real-time, letting you experiment with different scenarios to find the optimal approach for your situation.

Tips & Best Practices

  • Start with realistic values — use actual data when available rather than rough estimates for more meaningful results.
  • Compare scenarios — try different input combinations to understand how each variable affects the outcome.
  • Save your work — use the Share button to bookmark specific calculations for future reference.
  • Consult professionals — for critical decisions, use calculator results as a starting point and verify with a qualified expert.
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Frequently Asked Questions

Advanced 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.
Advanced 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%.
Advanced 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.
Basics 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.
Strategy 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.
Advanced 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.
Advanced 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.
Advanced 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.
Basics 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.
Advanced 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.
Advanced 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.
Basics 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.
Advanced 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.
Basics 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.
Basics 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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Formula & Methodology

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)
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Key Terms Explained

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.
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Real-World Examples

✈

NYC to London (+5h Eastward)

Transatlantic business travel route

Scenario: 5-hour eastward time zone shift from New York to London.

Result: 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.