Interventions to reduce short-wavelength ("blue") light exposure at night and their effects on sleep: A systematic review and meta-analysis

Ari Shechter; Kristal A Quispe; Jennifer S Mizhquiri Barbecho; Cody Slater; Louise Falzon

doi:10.1093/sleepadvances/zpaa002

Interventions to reduce short-wavelength ("blue") light exposure at night and their effects on sleep: A systematic review and meta-analysis

Sleep Adv. 2020 Jun 4;1(1):zpaa002. doi: 10.1093/sleepadvances/zpaa002. eCollection 2020.

Authors

Ari Shechter^{1

2}, Kristal A Quispe¹, Jennifer S Mizhquiri Barbecho¹, Cody Slater³, Louise Falzon⁴

Affiliations

¹ Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York, NY.
² Sleep Center of Excellence, Columbia University Irving Medical Center, New York, NY.
³ Columbia University Vagelos College of Physicians and Surgeons, New York, NY.
⁴ Center for Personalized Health, Feinstein Institutes for Medical Research, Northwell Health, New York, NY.

Abstract

The sleep-wake and circadian cycles are influenced by light, particularly in the short-wavelength portion of the visible spectrum. Most personal light-emitting electronic devices are enriched in this so-called "blue" light. Exposure to these devices in the evening can disturb sleep. Interventions to reduce short-wavelength light exposure before bedtime may reduce adverse effects on sleep. We conducted a systematic review and meta-analysis to examine the effect of wearing color-tinted lenses (e.g. orange or amber) in frames to filter short-wavelength light exposure to the eye before nocturnal sleep. Outcomes were self-reported or objective measures of nocturnal sleep. Relatively few (k = 12) studies have been done. Study findings were inconsistent, with some showing benefit and others showing no effect of intervention. Meta-analyses yielded a small-to-medium magnitude combined effect size for sleep efficiency (Hedge's g = 0.31; 95% CI: -0.05, 0.66; I² = 38.16%; k = 7), and a small-to-medium combined effect size for total sleep time (Hedge's g = 0.32; 95% CI: 0.01, 0.63; I² = 12.07%; k = 6). For self-report measures, meta-analysis yielded a large magnitude combined effects size for Pittsburgh Sleep Quality Index ratings (Hedge's g = -1.25; 95% CI: -2.39, -0.11; I² = 36.35%; k = 3) and a medium combined effect size for total sleep time (Hedge's g = 0.51; 95% CI: 0.18, 0.84; I² = 0%; k = 3), Overall, there is some, albeit mixed, evidence that this approach can improve sleep, particularly in individuals with insomnia, bipolar disorder, delayed sleep phase syndrome, or attention-deficit hyperactive disorder. Considering the ubiquitousness of short-wavelength-enriched light sources, future controlled studies to examine the efficacy of this approach to improve sleep are warranted. Systematic review registration: PROSPERO 2018 CRD42018105854.

Keywords: blue light; circadian; intervention; meta-analysis; short wavelength; sleep; systematic review.

Publication types

Review