Jet Lag: Common Questions
The mismatch between your body clock and local time after crossing time zones.
Last revised
Jet Lag: the questions people actually ask, answered from published guidance.
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 travelling.
- Commonest mistake: Alcohol on the flight, which worsens sleep quality.
- See a doctor if any of the signs under "When to get help" below apply to you.
What is Jet Lag?
The mismatch between your body clock and local time after crossing time zones.
Why does it matter?
Direction matters: travelling east compresses the day and is consistently harder to adjust to than travelling west.
Rough adjustment rate for Jet Lag?
About a day per time zone crossed.
Harder direction for Jet Lag?
Eastward.
Strongest tool for Jet Lag?
Timed light exposure.
What is the single most useful thing to do?
Shift your schedule by an hour a day for a few days before travelling.
What is the most common mistake?
Alcohol on the flight, which worsens sleep quality.
When should I see a doctor?
Seek urgent advice for calf pain, swelling or breathlessness after a long flight, which can indicate a deep vein thrombosis or pulmonary embolism. People with diabetes on insulin should plan dose timing with their diabetes team before crossing time zones.
Where to go next
- Making Sense of Jet Lag
- Jet Lag: A Practical Checklist
- Jet Lag — the reference entry
- What the Guidance Really Says About Insomnia
- Sleep Apnoea: Sorting the Evidence From the Noise
When to get help
Seek urgent advice for calf pain, swelling or breathlessness after a long flight, which can indicate a deep vein thrombosis or pulmonary embolism. People with diabetes on insulin should plan dose timing with their diabetes team before crossing time zones.
Where this comes from
- NHS — Jet lag
- The Sleep Charity — travel and sleep
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, summarised or generalised 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 a GP, 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 999.
