Jet Lag
Calculator
Estimate your recovery time based on circadian research. Get evidence-based tips for adjusting.
⚡ Personalize for accuracy
How Jet Lag Affects Your Body
Jet lag occurs when your internal circadian rhythm is out of sync with the local time at your destination. Your body clock, regulated by the suprachiasmatic nucleus in your brain, naturally runs on a cycle slightly longer than 24 hours (~24.2h on average).
This is why westward travel is easier—you're extending your day, which aligns with your natural rhythm. Eastward travel requires compressing your day, which your body resists more strongly.
Key Insight
Light is the most powerful signal for resetting your body clock. Strategic light exposure at the right times can significantly speed up your adjustment.
Days 0-2
Most symptoms
Adjusting
Improving gradually
Feeling Adjusted
Sleep and energy normalized
Why East vs West Makes a Difference
Your body clock naturally runs slightly longer than 24 hours. This makes westward travel (lengthening your day) easier than eastward travel (shortening it).
Traveling East
Harder adjustment
- 1Your day gets shorter (harder for your body)
- 2Need to go to bed earlier than usual
- 3Recovery: ~1 day per timezone crossed
- 4Early birds adapt slightly faster
- 5Seek morning light, avoid evening light
Traveling West
Easier adjustment
- Your day gets longer (natural preference)
- Need to stay up later than usual
- Recovery: ~0.7 days per timezone
- Night owls adapt slightly faster
- Seek evening light, dim late at night
Strategic Light Exposure
Light is the most powerful signal for resetting your body clock. Here's the general principle for most flights.
Seek Morning Light
Get bright outdoor light in the morning to advance your clock.
- Morning outdoor exposure
- Avoid evening bright light
- Dim lights before bed
Seek Evening Light
Get bright outdoor light in afternoon/evening to delay your clock.
- Afternoon outdoor exposure
- Stay active in evening
- Avoid early morning light
Complex Shifts
Large shifts need personalized timing—generic advice may backfire.
- Use specialized apps
- Consider jet lag direction
- Follow your body signals
About Our Estimates
Based on Circadian Research
Our estimates are based on published circadian rhythm research. Key findings we use:
- The human circadian period averages ~24.2 hours (Czeisler et al., 1999)
- Eastward travel (phase advance) is typically harder than westward (phase delay)
- Average adjustment rates of ~1 day/timezone east, ~0.7 day/timezone west
Ranges, Not False Precision
We provide recovery ranges rather than exact day predictions because:
- Individual variation is substantial
- Light exposure and behavior significantly affect recovery
- Large shifts (8+ hours) can be particularly unpredictable
What This Calculator Can't Do
This is an estimation tool based on population averages, not a personalized medical device. It cannot account for your specific flight timing, light exposure history, sleep quality, or individual circadian characteristics. For optimized jet lag management on important trips, consider using specialized apps developed with sleep scientists.
Ready for Your
Next Adventure?
TripMemo helps you capture memories even when jet lagged—with quick photo capture, voice notes, and day-by-day pages that make journaling effortless.
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Quick Capture
Photos + voice notes
Easy Journaling
Write when ready
Pin Places
Map your journey
Day Pages
Story by day
Frequently Asked Questions
Everything you need to know about jet lag and travel memories.
On average, jet lag lasts about 1 day per timezone crossed when traveling east, and about 0.5-0.7 days per timezone when traveling west. However, individual variation is significant—factors like light exposure, sleep timing, age, and personal physiology all affect recovery. These are estimates, not guarantees.
Related Reading
Learn More About Jet Lag
How Jet Lag Affects Your Travel Memories
Sleep disruption and fatigue from jet lag can affect how well you encode and recall experiences.
Read moreTravel JournalingThe 48-Hour Rule
Why you shouldn't force journaling right after landing—and what to do instead.
Read moreTravel ScienceEast vs West: Direction Matters
The science of circadian rhythms explains why eastward travel is harder.
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