Summarize this article:

Before you leave on your trip, start gradually shifting your sleep schedule to one that's in line with the place you're going. For instance, if there's a four-hour time difference between where you are and where you're going, starting shifting your sleep in that direction.  If you're going east, you'll gradually be going to bed earlier. For instance, if you live in New York and you're going to Scotland, that's a five-hour time difference. If you normally go to bed at 10 pm, that's 3 am in Scotland. Try shifting your bedtime 30 minutes earlier, and go to bed at 9:30 pm, which is 2:30 am in Scotland. The next night, try going to bed at 9 pm, and so on, until you get closer to your normal bedtime in the place you're going. If you're traveling west, it can be a bit harder to shift your schedule if you have to work at a certain time, because you'll be staying up later and later. If you have other conditions, such as diabetes or a breathing problem, it helps to have it under control before you leave. Be sure to take your medications and follow your doctor's orders. If you've been having trouble, talk to your doctor. If you're not feeling well, jet lag may affect you more, which could lead to mild depression. It can be easy to get dehydrated while traveling, since you're out of your normal routine and the air in airplanes is fairly dry. Dehydration can worsen the effects of jet lag, so make it a point to drink enough water. Buy a bottle of water when you get past security or take an empty bottle to fill up at a water fountain.  Take the drinks offered on planes, though stick to water and juice instead of alcohol, soda, or coffee to maximize hydration. Make sure to drink up before you leave home, as well. You can also try eating hydrating foods, such as watermelon, cucumbers, tomatoes, oranges, and soup. If you eat junk while you're traveling, you may end up feeling worse. Of course, you don't want to deviate too much from your normal diet (that can upset your stomach), but you should try to stick to healthier choices to increase your overall sense of well-being. If you know jet lag affects you particularly badly, try taking a slower form of travel, such as train or ship. Alternatively, stop over a few days somewhere halfway to where you're going. Taking it more slowly can help you adjust.

Summary:
Start shifting your sleep schedule. Make sure your health problems are under control. Drink enough water. Eat a healthy diet. Take a different means of transportation.