Effectiveness of Light Therapy in Cognitively Impaired Persons: A Metaanalysis of Randomized Controlled Trials

Objectives: To explore the effects of light therapy on behavioral disturbances (BDs), sleep quality, and depression. Design: Meta-analysis of randomized controlled trials. Setting: PubMed, Cochrane Library, Medline, EMBASE, Web of Science, and clinicaltrials.gov of selected randomized controlled trials and previous systematic reviews were searched. Participants: Cognitively impaired persons. Measurements: Information was extracted on study characteristics, quality assessment, and outcomes. Outcome measures included BDs, sleep quality, and depression. Results: Nine randomized controlled trials were examined. The results showed that light therapy has a moderate effect on BD (g = −0.61) and depression (g = −0.58) and a small effect on total sleep time at night (g = 0.25). Subgroup analysis indicated that a light intensity of 2,500 lux or greater has a greater effect on depression than an intensity of less than 2,500 lux (P =.03), and the low risk of bias in blinding was superior to the RCTs deemed to be of high or unclear risk of bias in blinding in terms of BD (P =.02). Conclusion: Light therapy can relieve BD, improve sleep quality, and alleviate symptoms of depression for cognitively impaired persons.