It's been ignored, but much can be done

The jet lag syndrome emerged with the rise of long haul air travel. The symptoms include disturbed sleep, increased fatigue, loss of concentration, and increased irritability during the new daytime, and yet difficulties in initiating and maintaining sleep at night. Long flights are also often tiring and uncomfortable (travel fatigue), and the dry cabin air contributes to dehydration. These effects can be distinguished from those of jet lag by comparing flights across time zones, for example from Europe to Asia, with flights of similar length along the same meridian, say to southern Africa, which cause travel fatigue but no jet lag. It is worth trying to minimise travel fatigue in its own right, and simple practical advice includes (see box).1

Jet lag is due to the desynchronisation between various body rhythms and environmental rhythms. The rhythm most noticeably affected is the cycle of sleep and activity, with the associated changes in physical and mental functioning. All the rhythms are regulated by internal and external factors that interact. For example, the “body clock” controls secretion of melatonin by the pineal gland, an important internal factor, and light turns it off. With a rapid change of time zone, it takes several days for the external factors to shift the phase of the body clock from …