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Blue light therapy delivered through light glasses improves sleep quality and daytime sleepiness in Parkinson's disease: A randomized trial

Śmiłowska K, de Vries NM, Bloem BR, van Wamelen DJ

Journal of Parkinson's disease, 2026

15 participants

Abstract

BackgroundSleep disturbances, including excessive daytime sleepiness (EDS) and fragmented nocturnal sleep, are common in Parkinson's disease (PD) and significantly reduce quality of life. This pilot study evaluated the efficacy of a novel approach using blue light, delivered via dedicated glasses with integrated LED lights, to improve sleep and non-motor symptoms.MethodsRandomised, placebo-controlled, single-blind pilot study with a 2-week light intervention. Participants were assessed at baseline, two weeks, and five weeks. The study was designed to evaluate between- and within-group changes. Participants were randomly allocated to receive blue light therapy (n = 15) or red light placebo (n = 15), delivered via LED-integrated glasses for one hour, twice daily, given for a 2-week period. Primary outcome was improvement in sleep quality, assessed via the Pittsburgh Sleep Quality Index. Secondary outcomes included diary-based sleep outcomes, excessive daytime sleepiness, mood, anxiety, and motor symptoms.ResultsThere was a significant group × time effect with blue light therapy leading to better Pittsburgh Sleep Quality Index scores (p = 0.021). Between-group analyses showed that at two weeks a trend toward significance was observed (p = 0.065), while sleep quality significantly improved at five weeks compared to placebo (p = 0.029) with a large effect size (0.896). Excessive sleepiness improved in the blue light group (p p = 0.005).ConclusionsBlue light therapy delivered…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 15 participants or records.

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