Patient-Oriented Evidence That Matters

Light Therapy Improves Behavioral Disturbances, Sleep, Depression in Older Patients with Cognitive Impairment


Am Fam Physician. 2018 Feb 15;97(4):online.

Clinical Question

Does light therapy improve sleep quality, depression, and behavioral problems in older patients who have cognitive impairment?

Bottom Line

In this meta-analysis, older patients with cognitive impairment who were exposed to light therapy had moderate improvements in behavioral disturbances, small improvements in sleep quality, and moderate improvements in depression. The authors did not report data on responders vs. nonresponders or on the potential adverse effects of treatment. (Level of Evidence = 1a)


These authors systematically reviewed multiple databases and clinical trial registries to identify randomized trials that evaluated the effect of light therapy on behavioral disturbances, sleep quality, and depression in older patients with cognitive impairment. Two authors independently assessed the risk of bias for each included study. They had high inter-rater reliability (kappa = 0.9), and tried to resolve disagreements through discussion; they used a third member of the team when agreement was not possible. They ultimately included nine trials with a total of 416 patients. The degree of cognitive impairment—based on results from the Mini-Mental State Examination—ranged from 5.7 to 22.1. The intensity of light in the studies ranged from 210 to 10,000 lux, and most of the patients were treated in the morning. The duration of light therapy ranged from one to 10 weeks (average = 5.4 weeks). Most control groups were exposed to average-strength indoor light; one study used no specific light as a control. None of the studies were considered to be of high methodologic quality, with the lack of masking being the most common concern. The pooled data from the five studies that evaluated behavioral disturbances showed moderate improvement with no statistical evidence for publication bias. Six studies that evaluated sleep quality showed small improvements and no statistical evidence for publication bias. Five studies that evaluated depression showed moderate improvements and no statistical evidence for publication bias. The authors did not report on potential harms of therapy, but I suspect there were not many.

Study design: Meta-analysis (randomized controlled trials)

Funding source: Government

Setting: Outpatient (any)

Reference: Chiu HL, Chan PT, Chu H, et al. Effectiveness of light therapy in cognitively impaired persons: a metaanalysis of randomized controlled trials. J Am Geriatr Soc. 2017;65(10):2227–2234.

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