The Effects of Light Therapy on Sleep, Depression, Neuropsychiatric Behaviors, and Cognition Among People Living With Dementia: A Meta-Analysis of Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 38216355 · doi:10.1016/j.jagp.2023.12.010
What was done
Authors conducted a systematic review and meta-analysis of randomized controlled trials across nine databases (Cochrane, ClinicalTrials.gov, Embase, EBSCOhost, Ovid-MEDLINE, PubMed, Scopus, Web of Science, and CINAHL). The study evaluated the effects of light therapy on sleep, depression, neuropsychiatric behaviors, and cognition in people living with dementia. Pooled effect sizes were calculated as Hedges' g using random-effects models. Study quality was assessed with the Cochrane RoB 2.0 tool, and heterogeneity was assessed with Cochrane's Q and I² tests.
What was found
A total of 24 studies comprising 1,074 participants were analyzed. Light therapy produced small-to-medium improvements in sleep parameters: total sleep time (Hedges' g = 0.19), wake after sleep onset (Hedges' g = 0.24), sleep efficiency (Hedges' g = 0.31), sleep latency (Hedges' g = 0.35), circadian acrophase (Hedges' g = 0.36), circadian amplitude (Hedges' g = 0.43), night awakenings (Hedges' g = 0.37), sleep disturbance (Hedges' g = 0.45), and sleep quality (Hedges' g = 0.60). Light therapy also reduced depression (Hedges' g = -0.46; cyclical function subscale g = -0.68; mood-related signs/symptoms subscale g = -0.84), reduced neuropsychiatric behaviors (Hedges' g = -0.34; agitation g = -0.65; affective symptoms g = -0.70; psychosis g = -0.72; melancholic behavior g = -0.91), and improved cognition (Hedges' g = 0.39).
Why it matters
This review provides quantitative evidence that non-pharmacological light therapy can simultaneously target multiple clinical domains in dementia, including sleep disturbances, mood, behavior, and cognitive function.
Limits
The abstract reports point estimates for Hedges' g but omits confidence intervals, p-values, and quantitative heterogeneity (I² and Q values). Specific light therapy parameters (lux, spectrum, duration, timing), adherence rates, dementia subtypes, and long-term durability of effects were not reported in the abstract. Average sample size per included trial was small (~45 participants).
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