
Jet lag, also called jet lag disorder, is a temporary sleep disorder that can affect anyone who quickly travels across multiple time zones. Jet lag is caused when your body’s internal clock or circadian rhythms, which tell your body when to stay awake and when to sleep in the old time zone, are out of sync with cues from the new time zone, such as light exposure and dining times. The more time zones crossed, the more likely you are to experience jet lag.
Jet lag can cause daytime fatigue, an unwell feeling, difficulty staying alert and gastrointestinal problems. Jet lag is temporary, but it can significantly reduce your vacation or business travel comfort. Fortunately, there are steps you can take to help prevent or minimize jet lag.
A key influence on your internal clock is sunlight. That’s because light influences the regulation of melatonin, which in turn is a synchronizing signal to cells throughout the body.
Certain cells in the tissue at the back of your eye (retina) transmit the signal of light to an area of your brain called the hypothalamus. At night, when this signal is low, the hypothalamus tells the pineal gland, a small organ situated in the brain, to release the hormone melatonin. During the day, the light signals to the hypothalamus result in the opposite, such that the pineal gland produces very little melatonin.
You may be able to ease your adjustment to your new time zone by exposing yourself to daylight in the new time zone so long as the timing of light is done properly.
Your body’s internal clock or 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. It involves exposing your eyes to an artificial bright light or lamp that simulates sunlight for a specific and regular amount of time during the time when you’re meant to be awake.
This may be useful, for example, if you’re a business traveler and are often away from natural sunlight during the day in a new time zone. Light therapy comes in a variety of forms including a light box that sits on a table, a desk lamp that may blend in better in an office setting or a light visor that you wear on your head.
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