How to beat jet lag and sleep on local time

Why jet lag disrupts sleep

Your internal clock runs on roughly a 24-hour cycle and drifts only slowly. When you cross several time zones, your bedtime arrives while your body still thinks it is afternoon, or you wake in the small hours because it is morning back home.

A 2010 review in the New England Journal of Medicine by Robert Sack describes jet lag as a mismatch between the body clock and the local day, and notes that symptoms are generally worse after eastward flights because the clock has to move earlier, which it does less easily than moving later.

Use light on purpose

Light at the right time moves your clock. Light at the wrong time moves it the other way.

• Flying west (for example Europe to the US): get bright light in the late afternoon and early evening locally. This helps you stay up and shifts your clock later.
• Flying east (for example the US to Europe): get bright light in the late morning, and avoid very early morning light for the first day or two by wearing sunglasses outside.
• At night, keep rooms dim and screens low. Bright light at night pushes your clock in the wrong direction.

Outdoor daylight is far brighter than indoor light, so a walk outside at the right time does more than any lamp.

A rough rule of thumb is that your clock shifts by about an hour or so per day when you help it with light, so a trip across six time zones can take several days to settle fully. Short trips of two or three days sometimes work better if you stay roughly on home time instead.

Meals, naps and caffeine

Eat on local time from the first day, even if you are not very hungry. Meal timing gives your body extra cues about where in the day it is.

Keep naps short, around 20 to 30 minutes and before mid-afternoon local time, so they do not eat into night sleep. Use caffeine in the local morning only. Late caffeine on a jet-lagged day stacks two problems.

Some travelers use melatonin to help with timing. Ask a pharmacist or clinician whether it suits you and when to take it, because timing matters and it is not right for everyone.

When you wake at the wrong hour

Waking at 3 or 4 AM local time in the first few nights is normal. Do not check your messages from home and do not turn on bright lights. Run a short, familiar reset: slow breathing such as 4-7-8, then an imagery task like the cognitive shuffle.

If you are still wide awake after a while, get up and do something quiet in dim light, then return to bed. Keep the next morning's wake time and light exposure on schedule. That steadiness is what helps your clock catch up. Sleeping in for hours to recover tends to make the next night harder.

A new hotel room adds its own disturbance on the first night. See the first-night effect for ways to make it easier.