0037 Tailored Lighting Intervention Improves Sleep and Cognition in Individuals with Mild Cognitive Impairment: Importance of Measuring Light Dose

Abstract Introduction Sleep disturbances are common in individuals with mild cognitive impairment (MCI) and are associated with worse cognition, mood, and risk of dementia progression. Our group previously showed that a tailored lighting intervention (TLI) designed to maximally affect the circadian system improves sleep and mood in individuals with Alzheimer’s disease and related dementia living in controlled environment, but its impact in community-dwelling individuals with MCI remains unclear. Methods We conducted a randomized, placebo-controlled trial of a home-based TLI in adults with MCI and sleep disturbances (N = 61; mean age = 69.7 years). Participants were randomly assigned to receive either active or placebo lighting for 24 weeks, with assessments at baseline, weeks 13, 25, and 37. Outcomes included sleep quality (Pittsburgh Sleep Quality Index PSQI), actigraphy-based sleep metrics, mood (Geriatric Depression Scale GDS), quality of life (Dementia Quality of Life DQoL), and cognition (ADAS-Cog and Montreal Cognitive Assessment MoCA). Circadian-effective light exposure was measured using a Daysimeter and summarized as area under the curve (AUC) for morning circadian stimulus (CS). Analyses used intention-to-treat and instrumental variable models to estimate causal effects of achieved light exposure. Results The active condition produced greater improvement in ADAS-Cog memory scores versus placebo (p = 0.035) and a trend toward improvement in total ADAS-Cog (p = 0.142). Morning CS AUC was higher in the active group by week 25 (0.021 vs –0.030; p = 0.025). Higher light exposure was associated with better sleep outcomes at week 25, including percent sleep (–0.21 vs –1.29 percentage points; p = 0.042), percent wake (–0.10 vs 1.19 percentage points; p = 0.023), and wake after sleep onset (2.19 vs 8.23 minutes; p = 0.031). Effects at week 37 were similar but not statistically significant. Conclusion A home-based light intervention for individuals with MCI was feasible and showed potential benefits for memory and sleep. Measuring actual light exposure was essential for understanding treatment effects. Support (if any) The NIA provided funding under grant number R01AG062288 and R01 AG034157.