Jet Lag

Jet lag results from a mismatch between a person’s circadian (24-hour) rhythms and the time of day in the new time zone. When establishing risk, clinicians should first determine how many time zones the traveler will cross and what the discrepancy will be between time of day at home and at the destination. During the first few days after a flight to a new time zone, a person’s circadian rhythms are still “anchored” to time of day at home. Rhythms then adjust gradually to the new time zone. A useful web-based tool for world time zone travel information can be found at www.timeanddate.com/worldclock/converter.html. If ≤3 time zones are being crossed, any symptoms such as tiredness are likely due to travel fatigue rather than significant jet lag, and will soon abate.

Many people traveling >3 time zones away for a vacation accept the risk of jet lag as a transient and mild inconvenience, while other people who are traveling on business or to compete in athletic events desire clear advice on prophylactic measures and treatments. If ≤2 days are spent in the new time zone, some people may prefer to anchor their sleep-wake schedule to time of day at home as much as is practical. Thereby, the total “burden” of jet lag resulting from the short round trip is minimized.