Jet Lag

Jet lag is a recognized sleep disorder that results from crossing time zones too rapidly for the circadian clock to keep pace. The pathophysiology involves a temporary misalignment between the circadian clock and local time.

How can the circadian rhythm be re-entrained after travel?
A traveler may be able to accelerate re-entrainment of the circadian rhythm by intentionally seeking out bright light at the optimal times of the day. A simple recommendation for travel across six to eight time zones is to seek exposure to bright light in the morning after eastward travel and in the evening after westward travel. It may also be useful to avoid light when exposure would impede adaptation; for example, it may be helpful for a traveler to stay indoors for the first few hours of daylight after long eastward flights or for a few hours before dusk after long westward flights. The timing of sleep does not, in itself, reset the clock.

How should sleep be strategically scheduled after travel?
Shifting one's sleep schedule by 1 or 2 hours towards congruence with the destination time zone before departure may shorten the duration of jet lag. Most travelers will be sleep-deprived after an overnight flight and will require extra (recovery) sleep on the first day or two after arrival. On subsequent days, short naps are effective in reducing daytime sleepiness, whereas longer daytime naps can undermine nighttime sleep, as well as reduce exposure to the re-entraining effects of light.

How should melatonin be used?
Melatonin can be considered to be a darkness signal. To promote shifting of the body clock to an earlier time after eastward travel, the author suggests that the traveler take 0.5–3 mg of melatonin at local bedtime nightly until he or she has become adapted to local time. For westbound travel, the author suggests taking 0.5 mg (low, short-acting dose) during the second half of the night until the traveler has become adapted to local time. Melatonin is not approved as a drug by the Food and Drug Administration (FDA).

Which hypnotics are most appropriate for use during flight?
Because there is limited opportunity to sleep during a flight, a hypnotic medication that has only a 2- to 3-hour duration of action (e.g., zaleplon) is preferred. A longer-acting sleeping pill (e.g., zolpidem or eszopiclone) could result in grogginess on arrival; a sleeping pill should not be taken if there is a risk of deep-vein thrombosis because the induced sleep may further increase that risk, and it should not be combined with alcohol.

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Teaching topics from the New England Journal of Medicine - Vol. 362, No. 5, February 4, 2010