Jet Lag Calculator
Estimate jet lag recovery time and get an optimal light-exposure and melatonin schedule based on time zones crossed and travel direction. Based on circadian science from NIH, CDC, and AASM.
Estimated Recovery (days)
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Severity —
Full Adjustment (days) —
Extended More scenarios, charts & detailed breakdown ▾
Recovery Days
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Severity —
Professional Full parameters & maximum detail ▾
Recovery Days
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Severity —
Melatonin Dose (mg) —
Circadian Disruption Risk —
How to Use This Calculator
- Enter time zones crossed and direction.
- Read estimated recovery days and severity.
- Use Light Schedule and Sleep Schedule tabs for countermeasures.
- Switch to Professional for age-adjusted recovery and melatonin dosing.
Formula
Recovery (east) = Time Zones × 1.0 days
Recovery (west) = Time Zones × 0.5 days
Age factors: senior ×1.3, under-30 ×0.8
Example
NYC → Tokyo = 13 zones eastbound: raw estimate 13 days; with melatonin + light strategy realistically 7–9 days.
Frequently Asked Questions
- Eastbound travel requires advancing your circadian clock — sleeping earlier than usual. The body naturally drifts slightly later, making it easier to delay sleep (westbound) than advance it. Rule: 1 day per zone east, 0.5 days per zone west.
- Yes. Research supports 0.5–3 mg taken 30 min before target bedtime for 3–5 nights to accelerate re-entrainment. Doses above 3 mg show no added benefit.
- Bright light is the strongest circadian cue. Morning light eastbound and afternoon light westbound shifts the body clock faster than any supplement.
- Crossing 7+ time zones is considered severe, with cognitive impairment and GI issues lasting 5–10 days without countermeasures.
Related Calculators
Sources & References (5) ▾
- NIH National Institute on Aging — Jet Lag & Sleep — NIH NIA
- CDC Travelers Health — Jet Lag — CDC
- AASM — Jet Lag Disorder — American Academy of Sleep Medicine
- Sleep Foundation — Jet Lag — Sleep Foundation
- Roenneberg T. — Internal Time (Harvard University Press, 2012) — Harvard University Press