USE OF BRIGHT LIGHT TO TREAT MALADAPTATION TO NIGHT-SHIFT WORK AND CIRCADIAN-RHYTHM SLEEP DISORDERS

Night work is associated with increased sleepiness and disturbed sleep . Maladaptation of the circadian system, which is phase-adjusted to da y time work and thus promotes sleepiness during its nadir at night and wakefulness (or disturbed sleep) during the day, contributes substant ially to this problem, A major cause of suboptimal circadian phase adj ustment among night workers is the exposure to morning light, which pr events the delay needed for optimal adjustment to night work. Several laboratory studies indicate that careful application of bright light m ay cause the circadian system to shift to any desired phase. Furthermo re, studies of simulated night work demonstrate that night exposure to bright light can virtually eliminate circadian maladjustment among ni ght workers. While the results are promising, there is still, however, an urgent need for longitudinal studies of bright light application i n real-life settings.