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Impact of ambient bright light on agitation in dementia
Ann Louise Barrick1, Philip D Sloane, Christianna S Williams
1Department of Psychology, University of North Carolina at Chapel Hill and Central Regional Hospital, NC, USA. ann.louise.barrick@dhhs.nc.gov
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 involving four ambient lighting conditions: AM bright light, PM bright light, All Day bright light, and Standard light. Sixty-six older persons with dementia participated. Outcome measures included direct observation by research personnel and completion by staff caregivers of the 14-item, short form of the Cohen-Mansfield Agitation Inventory (CMAI).
Results:
Analyses of observational data revealed that for participants with mild/moderate dementia, agitation was higher under AM light (p = 0.003), PM light (p < 0.001), and All Day light (p = 0.001) than Standard light. There was also a trend toward severely demented participants being more agitated during AM light than Standard light (p = 0.053). Analysis of CMAI data identified differing responses by site: the North Carolina site significantly increased agitation under AM light (p = 0.002) and PM light (p = 0.013) compared with All Day light while in Oregon, agitation was higher for All Day light compared to AM light (p = 0.030). In no comparison was agitation significantly lower under any therapeutic condition, in comparison to Standard lighting.
Conclusions:
Ambient bright light is not effective in reducing agitation in dementia and may exacerbate this behavioral symptom.
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