Circadian-based new technologies for night workers.

Night work is becoming increasingly common. Unfortunately, humans are physiologically unsuited to inverted schedules, leading to negative consequences for shift workers, employers, and society. The circadian and homeostatic processes which govern sleepiness and alertness are improperly aligned for night workers. We review a number of laboratory studies designed to treat circadian maladaptation to night work by shifting the circadian clock with light, exercise, or melatonin. There is substantial evidence that bright light treatments can successfully overcome the circadian misalignments associated with night work. The evidence for the efficacy of non-photic synchronizers such as exercise and exogenous melatonin is equivocal.. Nevertheless, our expanding scientific understanding of the nature of the problem has generated a promising range of options for shift workers.