Abstract
Jet lag emerges after flights across time zones, and abates when the circadian clock re-entrains to the light/dark cycle of the destination time zone. During the days of re-entrainment there is substantial circadian misalignment, with sleep, wake and meals occurring at the wrong circadian times. This misalignment produces difficulty initiating or maintaining sleep, excessive daytime sleepiness, decrements in performance, and gastrointestinal distress. We review how to shift the circadian clock using appropriately timed light, dark for sleep, and melatonin. Using these circadian rhythm principles, we describe how to make schedules for travelers which can reduce and even prevent jet lag.