Jet Lag

International travel is inevitable for elite athletes and their coaches, although many other people desire to exercise during international visits. The general travel fatigue associated with any international flight is quickly overcome, whereas jet lag is more long-lasting and is associated with desynchronization of circadian rhythms after time zones are crossed.

Jet lag symptoms, and their associated impact on athletic performance, depend on the duration and direction of the flight, the flight schedule, the time of day, and individual differences. Knowledge of the human circadian system can be used to develop interventions that accelerate adjustment of circadian rhythms and recovery from jet lag. In particular, the timing of outdoor or bright light exposure, meals, and exercise may be manipulated. Melatonin may be helpful, although daytime ingestion of this substance is discouraged among athletes, since it can induce drowsiness and can impair some aspects of athletic performance. Support staff should develop appropriate strategies for individual athletes, who might be assessed for chronotype (morningness/eveningness) or individual circadian phase (by measuring the circadian rhythm of core body temperature or salivary melatonin concentration). Informed strategies based on individual behavior can then be made to minimize the transient effects of jet lag on well-being and performance.