Beating Jet Lag With Light and Timing

Jet lag is not tiredness. It is a mismatch between your internal clock and the clock on the wall, and the fix is not sleep - it is re-timing.

What is actually happening

Your body runs on a circadian rhythm of roughly 24 hours, set primarily by light hitting your eyes. Cross several time zones quickly and that rhythm stays where it was for a while, telling you to sleep at lunchtime and to wake at three in the morning.

The rough rule is that you adjust about one time zone per day without intervention. With deliberate light exposure and meal timing, you can do noticeably better.

Why flying east is worse

Going west lengthens your day, and your internal clock naturally drifts slightly longer than 24 hours anyway. Staying up later is something your body can do.

Going east shortens your day and asks you to sleep before you are tired, which your body resists. Most people find eastward travel takes about fifty percent longer to adjust to.

Before you fly

If the trip is longer than a few days, start shifting.

• Flying east: go to bed and wake an hour earlier for two or three days before departure, and get bright morning light
• Flying west: shift an hour later, and get evening light
• Either direction: arrive rested. Sleep deprivation makes jet lag much worse and is entirely separate from it

On the plane

Set your watch to destination time as you board and start behaving accordingly. Eat when your destination eats. Sleep when it is night there, using the approach in our sleeping on planes guide.

Hydrate steadily and skip the alcohol. Dehydration mimics jet lag symptoms and adds nothing to the adjustment.

The first day

This is the day that decides how the rest of the trip feels.

1. Get outside into daylight as soon as you can after landing
2. Eat meals at local times even if you are not hungry
3. Stay awake until at least 9pm local, whatever it costs
4. If you must nap, set an alarm for 20 to 30 minutes and no more
5. Move - a walk is far better than a hotel room

Light timing is the powerful lever, and its direction matters. Travelling east, seek morning light and avoid bright light late in the evening. Travelling west, seek afternoon and early evening light, and avoid very early morning light for the first day or two.

Getting this backwards can genuinely delay adjustment, which is why lying in a dark hotel room all afternoon after an eastward flight feels good and helps nothing.

Caffeine, melatonin and sleeping aids

Caffeine is useful for getting through the first afternoon and harmful after about 2pm local. Use it deliberately, once, rather than steadily all day.

Melatonin is widely used for eastward travel, typically a low dose in the destination's early evening. It is regulated differently from country to country, evidence on dosing is mixed, and it is not appropriate for everyone. Ask a pharmacist or doctor rather than a forum.

Prescription sleep aids are a medical decision. They also do nothing to re-time your clock - they only mask the symptom.

Short trips

If you are somewhere for two nights, adjusting may not be worth it. Staying roughly on home time and scheduling meetings accordingly is often the better plan, and it means no re-adjustment when you get back.

Coming home

Do not neglect the return. Home jet lag is real and easier to ignore because life restarts immediately. Apply the same light and meal timing rules for two or three days, and expect the eastward leg - whichever direction that is for you - to be the harder one.