Your first class guide for preventing jet lag Image: © Tim Pannell/CorbisHave plane, will travel. Have travel, will also probably have jet lag, too. If you do experience jet lag, also known as desynchronosis, you'll probably experience insomnia, fatigue, even dehydration and headaches. It's considered a temporary sleep disorder. That's because crossing over time zones messes up our circadian rhythm, which can take up to several days — one day per time zone, says the New York Times — to adjust to the new daylight hours. The result? A cranky traveler.