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How to avoid jet lag — the science of light, sleep and caffeine
What jet lag actually is
Jet lag happens because the circadian clock in your brain is still running on home time. Symptoms — daytime sleepiness, broken nights, poor focus, stomach upset — become noticeable from about a 3-hour time difference and grow with distance, generally hitting harder when you fly east.
Light is the strongest tool
Bright light is the most powerful signal for shifting your body clock, and its effect flips depending on timing. Light after your body-temperature minimum (about 3 hours before your usual wake time) shifts the clock earlier; light before it shifts the clock later. A good plan uses this to nudge your clock a little every day.
East vs west
Because the human clock naturally runs a bit longer than 24 hours, delaying (westward) adjustment manages about 1.5 hours a day while advancing (eastward) manages only about 1 hour. And on eastward trips across more than 8 time zones, most bodies adjust "the long way round" — so planning a delay can actually be easier.
Before you fly
Shift your sleep and wake times by an hour a day toward your destination for 2–3 days before departure. You don’t need to absorb the whole difference — even 2–3 hours of head start helps.
On the plane
Sleep when it’s night for your body clock, not necessarily when the cabin lights dim. Drink water regularly; alcohol fragments sleep and dehydrates. Skip caffeine within 6 hours of any planned sleep.
After you land
Sleep on local time from the first night and get up with an alarm. If sleepiness is brutal, a 20–30 minute nap is fine — no more, and not in the late afternoon. Stop caffeine 6 hours before bed. Eating on local time may help your body settle in.
About melatonin
Some studies report melatonin reduces jet lag symptoms, but health agencies disagree — the UK’s NHS does not recommend it — and availability and quality standards vary by country. This site doesn’t recommend taking it; if you’re curious, talk to a doctor or pharmacist.
Sources
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