Jet Lag: The Quick Reference
Jet Lag: the whole thing in five minutes, for when you want the numbers and nothing else.
The mismatch between your body clock and local time after crossing time zones.
Key takeaways
- Rough adjustment rate: about a day per time zone crossed
- Harder direction: eastward
- Most useful single change: Shift your schedule by an hour a day for a few days before traveling.
- Commonest mistake: Alcohol on the flight, which worsens sleep quality.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
The numbers, in one place
| Measure | Figure |
|---|---|
| Rough adjustment rate | about a day per time zone crossed |
| Harder direction | eastward |
| Strongest tool | timed light exposure |
| Eastward | seek morning light at your destination, avoid evening light |
| Westward | seek evening light, avoid early morning light |
In one paragraph
Direction matters: traveling east shortens the day and is usually harder to adjust to than traveling west.
Worth doing
- Shift your schedule by an hour a day for a few days before traveling
- Switch to destination time as soon as you board
- Get outside at the right end of the day for your direction of travel
- Keep meals and activity on local time from arrival
Worth avoiding
- Alcohol on the flight, which worsens sleep quality
- Long naps on arrival, which delay adjustment
- Staying indoors for the first days
Related topics
- Teen Sleep: What Published Guidance Supports (Teen Health)
- Flying and Health: What Published Guidance Supports (Travel Health)
- What the Guidance Really Says About Shift Work and Health (Workplace Health)
- What the Guidance Really Says About Sleep and the Brain (Brain Health)
Where to go next
- Jet Lag: Sorting the Evidence From the Noise
- Making Sense of Jet Lag
- Jet Lag — the reference entry
- Sleep: The Complete Guide
- What the Guidance Really Says About Insomnia
- Sleep Apnea: What the Evidence Actually Says
When to speak to a doctor
See a doctor promptly for calf pain or swelling after a long flight, which can be a blood clot, and call 911 for sudden shortness of breath or chest pain, which can mean a clot has reached the lungs. People with diabetes who use insulin should plan dose timing with their care team before crossing time zones.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
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