Jet Lag & Time Zone Adjustment Planner

Plan your jet lag recovery with a personalized day-by-day schedule. Calculate jet lag severity, days to recover, and get science-backed tips for light, sleep, and caffeine.

Mathematical Audit

Jet Lag Severity & Recovery Formula

Jet lag severity is calculated based on the number of time zones crossed, direction of travel (eastward is harder due to circadian rhythm compression), and individual factors like age, exercise habits, and caffeine use. Recovery days are estimated at roughly 1 day per time zone crossed eastward, or 0.75 days westward.

Severity Score = Time Zone Diff × 0.7 × Direction Multiplier × Age Multiplier
Recovery Days (East) = ceil(Time Zone Diff × 1.0) − Exercise Bonus
Recovery Days (West) = ceil(Time Zone Diff × 0.75) − Exercise Bonus
Body Clock Drift = |Arrival Local Hour − Body Clock Hour|

Direction multiplier: East = 1.25, West = 1.0. Age multiplier: Under 30 = 0.85, 30-50 = 1.0, Over 50 = 1.2. Regular exercise reduces recovery by approximately 1 day. Eastward travel is harder because you must advance your circadian clock, which is harder than delaying it.

Operational Guide

How to Use the Jet Lag Planner

1

Enter your time zone difference

Enter the number of time zones between your departure and destination. New York to London = +5 (eastward); LA to Tokyo = +17 or -7 westward.

2

Select travel direction and flight duration

Choose whether you're flying east or west. Eastward travel is scientifically harder. Enter your total flight time.

3

Set your departure time

Enter the local time you depart. This affects what your body clock will think the time is when you land.

4

Enter your profile

Select age group (older travelers take longer to adjust), whether you exercise regularly, and your caffeine habits.

5

Get your recovery plan

Review jet lag severity score, estimated recovery days, a day-by-day adjustment schedule, and personalized tips on light exposure, sleep, and caffeine.

Real-World Scenario Example

"A 35-year-old regular exerciser flying east from New York (10 PM departure) to London (+5 time zones), 7-hour flight, coffee drinker."

Inputs

departureCity:New York
destinationCity:London
timezoneDiff:5
flightDurationHours:7
directionOfTravel:east
departureLocalHour:22
ageGroup:30-50
coffeeDrinker:true
exerciseRegularly:true

Result

Severity: Moderate (4.4/10). Recovery: 4 days. Body clock drift: 5 hours. Day 1 tip: Stay awake until 10 PM London time. Use caffeine only until 2 PM local.

Important Disclaimer

Jet lag severity and recovery estimates are based on scientific averages and may not reflect individual experiences. This tool does not provide medical advice. If you have a sleep disorder or medical condition, consult a healthcare provider before traveling across multiple time zones.

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Sources & References

Mayo Clinic — Jet Lag Disorder

https://www.mayoclinic.org/diseases-conditions/jet-lag/symptoms-causes/syc-20374027

National Institutes of Health — Circadian Rhythm and Jet Lag

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3839341/