I find meta-analysis are better for understanding the current state of research on a particular topic.
"A systematic search of PubMed, Scopus, and Web of Science identified randomized controlled trials (RCTs) from 2010 to 2024. Eligible studies enrolled adults using BBGs before bedtime and reported actigraphy-derived outcomes. Random-effects meta-analysis was performed using the generic inverse variance method. The review was registered in PROSPERO (CRD420251034611).
Results
Three double-blind crossover RCTs (n = 49) were included. BBGs showed a non-significant reduction in SOL (MD = −4.86 min; 95% CI: −20.23 to 10.52; p = 0.54) and a non-significant increase in TST (MD = 8.75 min; 95% CI: −35.31 to 52.82; p = 0.70). No significant effects were found for SE (MD = −0.61; 95% CI: −7.58 to 6.35; p = 0.86) or WASO (MD = −1.47; 95% CI: −14.94 to 11.99; p = 0.83). Heterogeneity was low (I2 = 0%).
Conclusion
BBGs may provide small improvements in sleep, but current evidence from RCTs does not support significant effects. Larger, well-powered trials with standardized protocols are needed."
- Efficacy of blue-light blocking glasses on actigraphic sleep outcomes: a systematic review and meta-analysis of randomized controlled crossover trials
- https://doi.org/10.3389/fneur.2025.1699303
given that phonescreens do not really dim the brightness and still flash lights in your face at full power just at slower intervalls does in a way confirm the point.
(See PWM dimming)
And a redlight filter just lowers the total brightness by shutting down the blue LED
that addresses the parent's last sentence, about blue light glasses, but not the "The blueness of the light doesn't matter" part, which is what all of my quotes addressed.
"A systematic search of PubMed, Scopus, and Web of Science identified randomized controlled trials (RCTs) from 2010 to 2024. Eligible studies enrolled adults using BBGs before bedtime and reported actigraphy-derived outcomes. Random-effects meta-analysis was performed using the generic inverse variance method. The review was registered in PROSPERO (CRD420251034611).
Results
Three double-blind crossover RCTs (n = 49) were included. BBGs showed a non-significant reduction in SOL (MD = −4.86 min; 95% CI: −20.23 to 10.52; p = 0.54) and a non-significant increase in TST (MD = 8.75 min; 95% CI: −35.31 to 52.82; p = 0.70). No significant effects were found for SE (MD = −0.61; 95% CI: −7.58 to 6.35; p = 0.86) or WASO (MD = −1.47; 95% CI: −14.94 to 11.99; p = 0.83). Heterogeneity was low (I2 = 0%).
Conclusion
BBGs may provide small improvements in sleep, but current evidence from RCTs does not support significant effects. Larger, well-powered trials with standardized protocols are needed."
- Efficacy of blue-light blocking glasses on actigraphic sleep outcomes: a systematic review and meta-analysis of randomized controlled crossover trials - https://doi.org/10.3389/fneur.2025.1699303