Bright light can phase shift human circadian rhythms, and recent studies have suggested that exercise can also produce phase shifts in humans. However, few studies have examined the phase-shifting effects of intermittent bright light, exercise, or the combination. This simulated night work field study included eight consecutive night shifts followed by daytime sleep/dark periods (delayed 9 h fr...

BACKGROUND Thirty-eight patients with SAD participated in a light visor study addressing two questions. 1. Can the development of a depressive episode be prevented by daily exposure to bright light started before symptom onset in early fall and continued throughout the winter? 2. Does the light have to be visible in order to have beneficial effects? METHODS Three groups participated in the st...

OBJECTIVE To evaluate the effect of ambient bright light therapy (BLT) on agitation among institutionalized persons with dementia. METHODS High intensity, low glare ambient lighting was installed in activity and dining areas of a state psychiatric hospital unit in North Carolina and a dementia-specific residential care facility in Oregon. The study employed a cluster-unit crossover design inv...

BACKGROUND Previous studies have shown that the human circadian system is maximally sensitive to short-wavelength (blue) light. Whether this sensitivity can be utilized to increase the size of phase shifts using light boxes and protocols designed for practical settings is not known. We assessed whether bright polychromatic lamps enriched in the short-wavelength portion of the visible light spec...

The unhealthy symptoms and many deleterious consequences of shift work can be explained by a mismatch between the work-sleep schedule and the internal circadian rhythms. This mismatch occurs because the 24-h zeitgebers, such as the natural light-dark cycle, keep the circadian rhythms from phase shifting to align with the night-work, day-sleep schedule. This is a review of studies in which the s...

Beneficial effects of napping or bright light exposure on cognitive performance have been reported in participants exposed to sleep loss. Nonetheless, few studies investigated the effect of these potential countermeasures against the temporary drop in performance observed in mid-afternoon, and even less so on cognitive flexibility, a crucial component of executive functions. This study investig...