LIGHT TREATMENT FOR SLEEP DISORDERS - CONSENSUS REPORT .7. JET-LAG

Sleep disturbances are an all-too-familiar symptom of jet lag and a pr ime source of complaints for transmeridian travelers and flight crews alike. They are the result of a temporary loss of synchrony between an abruptly shifted sleep period, timed in accordance with the new local day-night cycle, and a gradually reentraining circadian system. Sched uled exposure to bright light can, in principle, alleviate the symptom s of jet lag by accelerating circadian reentrainment to new time zones . Laboratory simulations, in which sleep time is advanced by 6 to 8 h and the subjects exposed to bright light for 3 to 4 h during late subj ective night on 2 to 4 successive days, have not all been successful. The few field studies conducted to date have had encouraging results, but their applicability to the population at large remains uncertain d ue to very limited sample sizes. Unresolved issues include optimal tim es for light exposure on the first as well as on subsequent treatment days, whether a given, fixed, light exposure time is likely to benefit a majority of travelers or whether Light treatment should be schedule d instead according to some individual circadian phase marker, and if so, can such a phase marker be found that is both practical and reliab le.