Effectiveness of morning blue light therapy on sleep and daytime symptoms in adults with primary and comorbid insomnia: A systematic review and meta-analysis of randomized control trials.

BACKGROUND

Insomnia is the most prevalent sleep complaint, occurring as a primary or comorbid condition, increasing the public healthcare burden. Prior reviews examined the efficacy of blue light therapy in improving sleep among patients with a traumatic brain injury and young adults and reported conflicting results. A comprehensive evaluation of blue light therapy on sleep quality, sleep parameters, daytime sleepiness, and fatigue across adults with primary insomnia and insomnia with comorbid condition has not been fully established.

METHODS

This study was conducted in accordance with the PRISMA 2020 statement. We searched EBSCO, Embase, OVID, PubMed, Scopus, Trials.Gov, Web of Science, and PROSPERO for eligible studies published between the date of database inception and 16 April 2025. The Cochrane risk of bias tool was used to assess study quality. A random-effects model was employed to calculate the pooled effects. Subgroup analyses were performed to identify potential moderators.

RESULTS

We included 14 articles involving 444 insomniacs with a neurological disease (mild traumatic brain injury, Alzheimer's disease, or dementia) or medical disease (cancer, diabetes, or fibromyalgia) or with no comorbidity. Studies were conducted in several Asian and European countries, as well as the United States and Australia. The results indicated that blue light therapy improved subjective sleep quality [mean difference (MD) = -1.895], excessive daytime sleepiness (MD = -0.970), and several objective sleep parameters [sleep onset latency (Hedges' g = -0.545), waking after sleep onset (Hedges' g = -0.563), sleep efficiency (Hedges' g = 0.429), sleep fragmentation (Hedges' g = -1.228), and number of awakenings (Hedges' g = -0.614)]. Blue light therapy did not improve the fragmentation index, time in bed, or total sleep time and did not significantly reduce fatigue. The type of device, intervention duration, and light intensity moderated sleep quality. The intervention duration and frequency moderated sleep efficiency.

CONCLUSIONS

In adults with insomnia with diverse clinical backgrounds, blue light therapy may provide modest improvement in sleep quality and certain sleep parameters related to advancement and continuity of sleep (sleep fragmentation, sleep onset latency, waking after sleep onset, number of awakenings, and sleep efficiency), and may alleviate excessive daytime sleepiness. These findings suggest that blue light therapy may be considered potential non-pharmacological treatment for insomnia that can be implemented by healthcare providers in home or clinical settings. However, these findings should be interpreted with caution. Further studies are needed to confirm these findings.

REGISTRATION: The review was registered with PROSPERO (CRD420251027417).