• Mayo Clinic Q and A: Prepare for jet lag before boarding the plane

a graphic representation of circadian rhythms and jet lagDEAR MAYO CLINIC: I recently took a new job that involves frequent overseas trips. The trips usually last four or five days, and include many business meetings. I’m concerned about jet lag and how it could affect my ability to be mentally sharp. Are there ways to prevent or minimize jet lag?

ANSWER: You’re wise to think about preventing jet lag before you leave home, rather than trying to deal with it once you’ve arrived at your destination. There are various steps you can take before you go that may ease jet lag.

Your body has an internal clock, or circadian rhythm, that signals when to stay awake and when to sleep. Jet lag happens because your body’s clock is still synced to your original time zone, instead of to the time zone where you’ve traveled. The more time zones you cross, the more likely you are to get jet lag.

In addition to sleep problems, jet lag can cause other symptoms that could disrupt your trips. Jet lag may lead to excessive daytime sleepiness and fatigue, as well as difficulty concentrating or functioning at your usual level. It also may lead to gastrointestinal problems, such as stomach upset, diarrhea or constipation. You may get headaches, experience mood changes and generally feel unwell due to jet lag.

To help prevent jet lag, a few days before your trip, start changing your schedule to more closely match your destination. For example, if you’re traveling east, which takes you to an earlier time zone, go to bed one hour earlier each night for a few days before you leave. If you’re traveling west, which takes you to a later time zone, go to bed an hour later for several nights. Adjust your meal schedule accordingly, too. And make sure you’re well-rested before you go, because starting a trip with too little sleep will make jet lag worse.

Switch to your destination schedule as soon as you leave home. Set your clocks to that new time when you get on the plane, and use it to guide your activities. If it’s nighttime in your destination when you’re in flight, sleep on the plane. Bring along earplugs, an eye mask and headphones to block noise and light, and make it easier to sleep. If it’s daytime where you’re headed, stay awake during the flight. Once you arrive, stick to the local schedule.

Dehydration may worsen jet lag symptoms. With that in mind, drink plenty of water or other beverages during your flight. Limit alcohol and caffeine, as they can dehydrate you and affect your sleep.

Exposure to bright light when you arrive at your destination can help your body adjust its circadian rhythm to your new schedule. For example, if you travel east, exposure to sunlight or other bright light in the morning can help you adapt. If you travel west, seek out light in the evening.

You need to be careful with this if you are traveling very long distances, though. If you’re more than eight time zones away from home, your body could confuse the light of morning with the light of evening, or vice versa, making your sleep issues worse. If you travel more than eight time zones to the east, avoid bright light in the morning. Then, seek out as much sunlight as possible in the late afternoon. If you go west by more than eight time zones, avoid sunlight a few hours before dark.

If you reach your destination and have trouble falling asleep at the appropriate time, over-the-counter sleep aids such as Tylenol PM or Advil PM may help. Taking a relatively low dose of melatonin (0.5 milligrams) — one of the strengths available over the counter — also has been shown to be effective. Prescription sleep medications (Ambien, Lunesta, others) can be helpful as well, but because they can lead to drowsiness the next day, these should be taken only as a last resort.

Finally, if you have a particularly important meeting, where you know you need to function at a high level, consider arriving a few days ahead of time, if possible. That will give your body time to adjust and make it less likely that you’ll feel the effects of jet lag when you need to be mentally sharp. — Dr. M. Rizwan Sohail, Travel Medicine, Mayo Clinic, Rochester, Minnesota