Your bag is packed and your flight awaits. You're excited about your vacation plans, or maybe you're looking forward to that work conference.

What you're not looking forward to is the jet lag.

Jet lag — that fatigued feeling you get when traveling over 3 or more time zones — is common. It can make it difficult to sleep, concentrate and stay motivated. It can also make you feel crabby, cause headaches or trigger digestive issues.

If you're traveling especially long distances, your jet lag may be even worse. Travel fatigue often becomes more pronounced the more time zones you cross.

In fact, it takes roughly 1 day to fully adapt to your destination's time zone for every 3 zones you cross traveling eastward. Adapting is typically easier for westward travel, which takes about 1 day to adapt for every 1.5 time zones crossed.

While there's no way to completely avoid jet lag and travel fatigue, this advice can help.

Before you leave

Get good sleep in the nights leading up to your trip.

• For eastward travel: Go to bed 30 to 60 minutes earlier for 3 nights before travel, and avoid evening light, including electronics. Expose yourself to bright, natural light in the mornings.
• For westward travel: Go to bed 30 to 60 minutes later for 3 nights before travel. Also wake up later than usual, and avoid bright light for a couple of hours. This may mean wearing sunglasses and staying off electronic devices.

While you travel

• Set your watch to your destination time. Attempt to sleep or at least be in the dark during your destination's nighttime, and stay awake during destination daytime.
• Drink plenty of water. This will help you avoid dehydration, which may contribute to some of the symptoms of jet lag.
• Limit alcohol. You should also avoid caffeine.
• Wear foam earplugs or noise-canceling headphones. These can reduce engine or cabin noise so you can sleep. An eye mask can help provide darkness.
• Avoid sleeping pills on the flight. Drowsiness and disorientation may linger after landing.

When you arrive at your destination

• Lock into the local time. This may involve staying awake when you're tired or going to bed when you're not.
• Consider taking a low dose of melatonin. If you're traveling eastward, or over 12 time zones westward, ask your doctor about taking melatonin before bedtime.
• Take a nap. If you arrive in the morning, a 20- to 30-minute nap can help you make it to destination bedtime.
• Watch your caffeine intake. Caffeinated drinks can help you stay alert, but should be avoided after midday.
• As a last resort, consider a sleeping pill. If you're having trouble sleeping at your destination nighttime, a sleeping pill may help. Talk to your doctor for recommendations.

How light exposure can help

Traveling across multiple time zones takes its toll. But you can use light exposure to your advantage. Consider this advice depending on how far you're traveling.

When traveling east:

• 6 to 8 time zones: Avoid early and midmorning light for a few days, then seek it out by late morning. Morning light is fine if crossing 5 or fewer time zones.
• More than 8 time zones: Seek early morning light and avoid bright evening light for a few days.

When traveling west:

• 8 or fewer time zones: Seek out light in the afternoon and evening, and avoid light during normal sleeping hours.
• More than 8 time zones: Seek out light from midmorning to late afternoon, and avoid bright evening light for a few days.