Jet lag is caused by flying in an airplane and crossing one or more time zones, which can disrupt the body's sleep and wake cycle (circadian rhythms). Jet travel across time zones may make it difficult for you to fall asleep, stay asleep, or stay awake during the day.
The effects of jet lag usually are greater if you are going from west to east than from east to west.
The symptoms of jet lag take a few days to go away:1
Melatonin is a hormone the body makes that regulates the cycle of sleeping and waking. Taking melatonin may help "reset" your sleep and wake cycle. Studies note that using it has reduced how much jet lag people report on both eastward and westward flights.2
You can try taking melatonin to reduce the symptoms of jet lag. Suggestions about times and dosages vary among researchers who have studied melatonin. Recommendations include:
The long-term side effects of melatonin have not been well studied. If you have epilepsy or are taking blood thinners such as coumadin (Warfarin), talk to your doctor before using melatonin.
There are other things you can do to decrease the effects of jet lag. Be rested before your flight, and try to walk around during the flight so that you are not confined to cramped spaces for long periods of time. Drink lots of water, because the air in jets tends to be dry. Vitamins and herbal remedies that can be bought without a prescription can also be tried to help reduce jet lag.
Citations
Waterhouse J, et al. (2007). Jet lag: Trends and coping strategies. Lancet, 369(9567): 1117–1129.
Herxheimer A (2007). Jet lag, search date November 2006. Online version of BMJ Clinical Evidence. Also available online: http://www.clinicalevidence.com.
Herxheimer A, Petrie KJ (2007). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews (2).
WebMD Medical Reference from Healthwise