Sleep and intercontinental flights.

At present there are no 'high-tech' solutions to the problems that may beset intercontinental travellers. Indications for the use of drugs are limited, and their use must accord with Good Clinical Practice. Essentially, travellers must look after their sleep, as far as possible, during and after the flight. The most useful time for sleep during the flight must be anticipated, caution exercised in the use of hypnotics in-flight as reduced mobility is a potential risk factor for venous thrombosis, and a strategy adopted, whether flying east or west, to adapt as quickly as possible to the working hours of the new locality. After an eastward flight a hypnotic may be useful, but this strategy is seldom necessary after a westward flight unless the journey has involved crossing more than 5 or 6 time zones. The claim that melatonin accelerates the shift of the sleep-wakefulness cycle to a new time zone is controversial, and its recommended use may prejudice alertness during working hours. Exposure to artificial light and avoidance of ambient light at certain times of the day could prove to be of help-possibly in conjunction with drugs. However, effective and practical alterations in the light environment must be devised before such strategies can be considered with confidence.