The effects of light therapy on sleep, agitation and depression in people with dementia : a systematic review and meta-analysis of randomized controlled trials

Abstract

Objective: To evaluate the effects of light therapy on the alleviation of sleep disturbances, agitation and depression in people with dementia. Methods: A search was performed in PubMed, Medline, SCOPUS, Web of Science, EMBASE, CINAHL, Cochrane Library, for studies published between 2000 and 2021. Results: A total of 4315 articles were screened. Sixteen articles were eligible for this review and 11 randomized controlled studies were included in the meta-analysis. Light therapy had a significant effect on reducing the number of awakenings in sleep (n = 4; 95% CI = −.56, −.05; I2 = 0%; SMD = −.31) but was not significant in reducing the wake after sleep onset (n = 3; 95% CI = −.14, .59; I2 = 0%; SMD = .23), agitation (n = 4; 95% CI = −1.02, .45; I2 = 87%; SMD = −.28) and depression (n = 6; 95% CI = −.80, .40, I2 = 85%; SMD = −.20). Conclusion: Light therapy appeared to be more effective in terms of alleviating sleep disturbances, rather than reducing agitation and depression, but its long-term effects remain unclear.