Jet lag can be a problem for athletes who travel across time zones. Excessive fatigue and disturbances of the athlete's body clock can have effects on feelings of fatigue and performance. What exactly is jet lag? and what can we do about it? Below is an interview with Dr Shona Halson and Prof Neil Walsh based on a multi-author review paper on sleep and jet lag that was recently published in the British Journal of Sports Medicine (1). What is jet lag exactly and what causes it