One of the challenges of modern football and the international game is the need to play in different cities and countries around the world and in different time zones. There is also the matter of providing medical care for athletes in a new and foreign environment. To be able to do this effectively requires careful planning.
One of the results of international travel is jet lag – the disruption of the normal circadian rhythm and a mismatch between the ‘‘body clock time’’ and the new local time. This results in a variety of mental and physical effects. The more time zones crossed, the more severe and lasting the jet lag symptoms, and the latter are usually worse after flying eastwards than westwards. This appears to be because the body’s circadian set-up naturally adapts better to westward travel.
Jet lag must be differentiated from travel fatigue, which can occur even when travelling north or south without changing time zones.