Jet lag, or desynchronosis, is a temporary condition that some people experience following air travel across several time zones in a short period of time. This causes the traveler's internal clock to be out of sync with the external environment.
Jet lag occurs while rapidly crossing time zones. More specifically, it occurs after crossing the Earth's meridians. Meridians demarcate geographic position in relation to the Earth's poles and define time zones. Jet lag is a unique, temporary sleep disorder because its onset is not necessarily caused by abnormal sleep patterns, like insomnia.
Symptoms of jet lag can vary per person. Symptoms may include:
Jet lag symptoms usually occur within a day or two of travel if you've traveled across at least two time zones. Symptoms are likely to be worse or last longer the more time zones that you've crossed, especially if you travel in an easterly direction. Although jet lag occasionally lasts for a week or more, travelers usually return to their normal sleep-wake pattern after a day or two. It's estimated to take about a day to recover for each time zone crossed.
Your body's circadian rhythms are influenced by exposure to sunlight, among other factors. When you travel across time zones, your body must adjust to a new daylight schedule and reset, allowing you to fall asleep and be awake at the appropriate times. Light therapy can help ease that transition.
Traveling East: Seek light therapy in the morning (destination time).
Traveling West: Seek light therapy in the evening (destination time).