0436 Is Bright Light More Effective Than Dim Light in Improving Sleep Among Individuals with Cancer? A Meta-Analysis

Abstract Introduction Disrupted sleep is common in cancer patients due to dysregulated circadian rhythm. Studies reported that bright light therapy (BLT) improves insomnia in cancer patients. However, dim light controls have also been shown to improve insomnia symptoms, contradicting the current belief that bright light is superior to dim light. This meta-analysis examined the effects of BLT on sleep in adult cancer populations and explored potential moderators including individual and BLT-related characteristics. Methods A comprehensive search (updated in October 2025) was performed in PubMed, CINAHL (EBSCO), Embase, and Web of Science Core Collection. Meta analyses were conducted using the Comprehensive Meta-Analysis Software version 4. Random effect models assessed pooled effect sizes. Cochran’s Q test and I2 statistics evaluated study heterogeneity. Overall sleep quality was measured by Pittsburgh Sleep Quality Index global scores. Results The searches identified a total of 1,721 citations. Ten randomized controlled trials were included in this meta-analysis. BLT was moderately effective in improving patient-reported sleep quality (g=0.49; 95% CI: 0.04, 0.95; p=.034). Intensity of dim light control (Q=13.07, p=.023) and duration of BLT (Q=13.11, p=.022) were significantly associated with intervention effects. The greatest effects were observed in studies with dim light control of 50 lux (g=1.03; 95% CI: 0.06, 2.00) and therapy duration of 1 week (g=0.89; 95% CI: 0.03, 1.75). BLT had small effects on decreasing actigraphy- or polysomnography- measured sleep onset latency (g=0.39; 95% CI: 0.05, 0.74) and increasing sleep duration (g=0.31; 95% CI: -0.05, 0.66). Noticeably larger effects were reported in studies included both males and females than females only (g=0.61 vs. 0.37, p=.610), mixed cancer types than breast cancer only (g=0.69 vs. 0.22, p=.337), and more non-White than White-dominated participants (g=0.46 vs. 0.25, p=.684). The findings were favorable to dim light for patient-reported sleep onset latency (g=-0.52; 95% CI: -1.27, 0.24). Conclusion This meta-analysis supports that BLT is superior to dim light in improving patient-reported sleep quality and objectively measured sleep onset latency. BLT may be beneficial to patients across different cancer types and treatment status. Shorter therapy durations, and potential sex- and race-differences in the BLT effects demand further investigation. Support (if any) None