Jet lag refers to the misalignment of your body’s internal clock with the local time at your destination. This phenomenon often occurs when flying across three or more time zones. Jet lag can throw off your sleep and cause other bothersome symptoms that persist for days or even weeks after a flight.

Jet lag, also called jet lag disorder, is a temporary sleep problem that can affect anyone who quickly travels across several time zones. Your body has its own internal clock, called circadian rhythms. They signal to your body when to stay awake and when to sleep.

Jet lag is a physiological condition that results from alterations to the body's circadian rhythms caused by rapid long-distance trans-meridian (east–west or west–east) travel.