What is it? Also known as time-zone change, jet lag is a disruption in sleep patterns following travel across time zones. It occurs because the traveler's internal "clock" is out of sync with the new time zone. Symptoms include difficulty falling asleep, difficulty arising, and disrupted sleep, all leading to daytime sleepiness, headache and general malaise.
How common is it? Jet lag is a common problem for travelers, and more common in those over 50 than in those under 30. Incidence varies depending on how many time zones and the direction of travel. When traveling westward, the traveler's internal clock is ahead of local time and the traveler typically tires early and awakens early. When traveling eastward, the traveler's internal clock is behind local time and the traveler typically falls asleep and awakens later than local time, and often is very sleepy during the day and particularly in the morning. These effects may be felt a day or two after travel. Frequent travelers can develop chronic jet lag symptoms.
What's the treatment? In general, traveling westward is easier than traveling eastward. A westward traveler can make up for about a 1.5-hour difference per day; an eastward traveler makes up about one hour per day. Adjusting to travel from Los Angeles to New York, for example, (a three-hour time difference) would take three days, but only two days on the return trip.
Some steps that can minimize the effects of jet lag are to adjust your sleep schedule to the new location during the days preceding your trip. Avoid alcohol and caffeine during your trip. Both can effect the quality of your sleep. Taking 5 mg. of melatonin at bedtime during the first few days following arrival may help in adjustment. Some prescription short-acting hypnotics can help relieve jet lag. Exercise and keeping well hydrated (with nonalcoholic or caffeine-free drinks) can also help in the adjustment to a new time zone. Light therapy, as used in advanced and delayed sleep disorders, may help in adjustment.