How to Get Over Jet Lag

Why jet lag happens

Your body runs on an internal clock with a cycle of roughly one day, and sleepiness, body temperature, digestion and alertness all follow it. When you fly across several time zones, the outside day and night change at once, but the internal clock only catches up a little each day. The mismatch in between shows up as daytime drowsiness, sleepless nights, an upset stomach and a foggy head. So getting over jet lag is not about willpower. It is about which way you need to move your body clock and how quickly you can do it.

Why east is harder

For most people the body clock tends to run slightly longer than a day, so shifting later is relatively easy and shifting earlier is hard. Flying east shortens your day and forces the clock earlier; flying west lengthens it, so you only need to stay up later. That is why many people find it harder to fall asleep after an eastbound trip, even across the same number of time zones. Individual differences are large, though, and whether you are a morning or evening person matters too.

Light is the strongest signal

Of all the cues that move your body clock, light entering your eyes is the most powerful. When you need to shift earlier, get plenty of local morning daylight and cut down on bright light in the evening. When you need to shift later, seek light in the afternoon and evening and avoid strong light early in the morning. After a very large time difference, bright light at the wrong moment on day one can push you the wrong way, so on the first day it is safer to spend time outside around midday than to chase dawn sunlight.

What to do a few days before

If you have time to prepare, moving your bedtime a little toward the destination's schedule for a few days before departure makes arrival easier. Going east, go to bed and get up a bit earlier each day; going west, a bit later. Pulling an all-nighter before the flight may seem like a way to sleep on the plane, but arriving short on sleep often makes adjusting harder.

• Shift your bedtime gradually toward the destination for a few days
• Sleep normally the night before you leave
• Check whether you land in the local morning or at night
• Keep the first day's plans light

On the plane

Once you board, set your watch to destination time and decide whether to sleep or stay awake based on that. If it is night there, block light and noise with an eye mask and earplugs and rest; if it is daytime, stay awake as much as you can. Cabin air is dry, so drink water often. Alcohol may seem to help you drop off, but it lowers sleep quality and adds to dehydration. Cut back on caffeine too if it is afternoon or later at your destination. On long flights, getting up now and then to walk the aisle and move your legs also eases fatigue.

Rules for arrival day

When you land, match meals, activity and sleep to local time. If you arrive during the day and feel overwhelmed, take a very short nap and get up right away; sleeping for hours tends to wreck the night. A gentle walk outside in daylight is the most reliable remedy. If you wake at night and cannot get back to sleep, keep the lights low and avoid staring at your phone. Adjusting usually takes several days, and the larger the time difference, the longer it takes.

If the trip is short

On a short trip of two or three days, you would be heading home just as your body finishes adjusting. In that case it can make more sense not to shift much at all and to schedule important things during the hours when your body is naturally alert. The same principles apply when you come back, so avoid packing the day after your return with important commitments. If you are staying a week or more, on the other hand, switching fully to local time from day one gets you comfortable sooner.

Sleep aids and other cautions

Sleep aids and hormone supplements marketed for jet lag are regulated differently from country to country and may not suit you depending on your medications or health conditions. Always check with a pharmacist or doctor before taking them, and never try a sleeping pill for the first time on a flight. This article is general information. If insomnia or severe fatigue persists long after you return, see a medical professional.

• Discuss and try any new medication before the trip
• Do not combine alcohol with sleeping pills
• Avoid driving or big decisions when drowsy