Jet Lag Calculator

The Jet Lag Calculator is a science-based tool that generates a personalized recovery plan for your specific trip. Enter your departure and destination cities, travel dates, and your chronotype (morning lark, neutral, or night owl) to receive a detailed day-by-day schedule with light exposure timing, caffeine cutoffs, melatonin guidance, and sleep targets.

Unlike generic advice, this calculator uses DST-aware timezone calculations to determine the exact offset for your travel dates, accounts for whether you are traveling eastbound or westbound, and adjusts recommendations based on your natural sleep preferences.

Jet lag occurs when your circadian rhythm (internal body clock) is out of sync with the local time at your destination. Your body uses light, meal times, and social cues to maintain a roughly 24-hour cycle. When you cross multiple time zones rapidly by air, these external cues suddenly shift but your internal clock does not — resulting in fatigue, insomnia, digestive issues, and difficulty concentrating.

The key to recovery is strategic light exposure. Light is the strongest signal for resetting your circadian rhythm. For eastbound travel (advancing your clock), seek morning light. For westbound travel (delaying your clock), seek evening light. The calculator provides precise timing for each day of your recovery.

Eastbound travel is harder because it requires you to advance your body clock — go to sleep earlier and wake up earlier than your body wants. Since the human circadian rhythm naturally runs slightly longer than 24 hours, shortening the day goes against our biology. Recovery typically takes about 1 day per timezone crossed.

Westbound travel is easier because delaying your clock — staying up later — aligns with our natural tendency toward a longer day. Recovery is faster, typically 0.75 days per timezone crossed. A trip from London to New York (5-hour difference) might take just 3-4 days to fully recover from.

• Pre-adapt before you fly — shift your sleep schedule by 30-60 minutes per day for 3 days before departure in the direction of your destination timezone.
• Hydrate aggressively — airplane cabins have 10-20% humidity. Dehydration amplifies fatigue and jet lag symptoms. Drink water throughout the flight.
• Time your meals — eating on local time from the moment you arrive is one of the most effective signals for resetting your body clock.
• Resist long naps — if you must nap, keep it under 20 minutes. Longer naps make it harder to fall asleep at the local bedtime.
• Get outside — natural light is far more powerful than indoor light for circadian reset. Even overcast daylight is 10-50x brighter than indoor lighting.