Objective: 

Aged individuals show disturbances in sleep and general activity. These changes have been attributed to disruptions in the circadian clock caused by dampening of the light exposure in institutionalized patients. This report aims at recording the activity and body temperature to assess sleep disturbances in aged patients with mild to severe dementia after exposure to bright light.

Methods: 

Activity, body position, light exposure and wrist temperature has been continuously monitorized during three weeks in 11 elderly (mean age 75) institutionalized subjects with Alzheimer dementia, mild cognitive deficits and sleep disturbances using Hobo sensors for light exposure, activity and body position. Ibuttons (Maxim ®) were also used to record wrist temperature (Cronobiotech, R&D). The first week was used as baseline. During the second week the subjects were submitted to bright light treatment (10000 lux, 90 min daily) and the third week to observe the eventual carry over effects.

Results: 

As a general result, sleep and circadian rhythms of the subjects were improved after exposure to bright light, increasing the amplitude of the temperature and activity daily rhythms and causing a 90 min phase delay in activity.

Conclusions: 

The bright light therapy caused significant improvements in indicators of sleep and activity circadian rhythms of institutionalized elderly subjects.