Jet Lag

It's also why you might doze off at lunch on your first day in London or be unable to get to sleep the first couple of nights of a vacation to Japan. | You can use strategically timed naps and caffeine to ease into your new time zone. | Hop a plane across several time zones, and you may end up with what scientists call circadian dysrhythmia, also known as jet lag. | But jet lag doesn't have to wreck your trip. | It's a temporary sleep disorder where your body's internal clock isn't in sync with the time cues in your destination.