Jet lag is a physiological condition that the body's circadian rhythms is out of synchronization with the destination time when people travel across a number of time zones and experience daylight and darkness contrary to the rhythms that their body have been accustomed to. When traveling abroad by air, the body clock will in disorder due to the jet lag and people may fell dizzy; it is medically called "the syndrome of jet lag". For patients with severer conditions, there may be headache, tinnitus, palpitation, nausea, abdominal pain, diarrhea and the decreasing of sense and attention.
