How jet lag works
Your circadian rhythm
Your body runs on an approximately 24-hour internal clock, regulated primarily by the suprachiasmatic nucleus (SCN) in the brain. This clock controls when you feel sleepy, alert, hungry, and when hormones like melatonin and cortisol are released.
The primary synchronizer of this clock is light — specifically, bright light reaching specialized photoreceptors in your eyes. This is why light exposure timing is the most important factor in jet lag recovery.
Why time zone changes cause jet lag
When you fly across time zones, your internal clock is misaligned with the local day-night cycle. Your body "thinks" it's one time while the environment says it's another. This mismatch causes the familiar symptoms: fatigue, insomnia, difficulty concentrating, digestive issues, and general malaise.
East vs. west
Eastward travel (advancing the clock) is generally harder because it requires going to sleep earlier than your body wants — which is more difficult than staying up later. Your body adjusts at roughly 1–1.5 hours per day, with westward adjustment often being slightly faster.
Recovery strategies
- Light exposure: The most effective tool. Seek bright light at strategic times based on direction.
- Sleep schedule: Gradually shift toward the destination time zone.
- Meal timing: Eating at local meal times helps reset peripheral clocks.
- Caffeine: Useful for maintaining alertness but must be timed carefully.
- Hydration: Dehydration worsens fatigue — drink water throughout travel.
- Short naps: 20–30 minute naps can help; longer naps may delay adjustment.
When to seek professional help
If you travel frequently and experience persistent sleep issues, or if you have pre-existing sleep disorders, consult a healthcare professional. They may recommend specific interventions beyond general guidance.