Association between exposure to light at night (LAN) and sleep problems: A systematic review and meta-analysis of observational studies

Yu-Xiang Xu; Jiang-Hui Zhang; Fang-Biao Tao; Ying Sun

doi:10.1016/j.scitotenv.2022.159303

Association between exposure to light at night (LAN) and sleep problems: A systematic review and meta-analysis of observational studies

Sci Total Environ. 2023 Jan 20;857(Pt 1):159303. doi: 10.1016/j.scitotenv.2022.159303. Epub 2022 Oct 10.

Authors

Yu-Xiang Xu¹, Jiang-Hui Zhang², Fang-Biao Tao³, Ying Sun⁴

Affiliations

¹ Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, Hefei, Anhui, China.
² Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei 230032, China.
³ Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, Hefei, Anhui, China; Key Laboratory of Population Health Across Life Cycle (Anhui Medical University), Ministry of Education of the People's Republic of China, No 81 Meishan Road, Hefei 230032, Anhui, China; Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, Anhui, China.
⁴ Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, Hefei, Anhui, China; Key Laboratory of Population Health Across Life Cycle (Anhui Medical University), Ministry of Education of the People's Republic of China, No 81 Meishan Road, Hefei 230032, Anhui, China; Anhui Provincial Key Laboratory of Population Health and Aristogenics, Anhui Medical University, No 81 Meishan Road, Hefei 230032, Anhui, China. Electronic address: yingsun@ahmu.edu.cn.

PMID: 36228789
DOI: 10.1016/j.scitotenv.2022.159303

Abstract

Background: Accumulating evidence have investigated the effects of nighttime light exposure on sleep problems. Nevertheless, the evidence of the relationship between light at night (LAN) and sleep problems remains scarce and inconsistent.

Objective: Conducted a systematic review and meta-analysis based on observational studies to examine the association between LAN exposure and sleep problems among human subjects.

Methods: We systematically searched three databases (PubMed, Web of Science, and Embase) to identify potentially eligible studies through May 25, 2022. The risk of bias and the quality of the generated evidence were assessed by two authors using the National Toxicology Program's Office of Health Assessment and Translation (OHAT) risk of bias rating tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guideline. Random-effects model was applied to synthesize the risk estimates across eligible studies. The heterogeneity of included studies was quantified by the statistics of I².

Results: A total of 7 cross-sectional studies comprising 577,932 participants were included. Individuals with higher levels of LAN exposure were associated with a 22 % (Summary Odds Ratio, SOR: 1.22, 95 %CI: 1.13-1.33) increased prevalence of sleep problems. The pooled effect size of indoor LAN exposure (SOR: 1.74, 95%CI: 1.27-2.37) associated with sleep problems was significantly higher than outdoor LAN exposure (SOR: 1.19, 95%CI: 1.11-1.29; P = 0.022). Additionally, dose-response analysis demonstrated that LAN intensity threshold exceeding 5.8 nW/cm²/sr (SOR: 1.04, 95%CI: 1.01-1.07) had a significant effect on sleep problems and the prevalence of sleep problems was increasing with increase in LAN intensity.

Conclusions: Overall, our findings support the detrimental effects of LAN exposure on sleep. Maintaining bedroom darkness at night may be a feasible measure to reduce the prevalence of sleep problems. Future longitudinal studies with more advanced LAN assessment methods are required to move the field forward.

Keywords: Dose-response meta-analysis; Light at night; Light pollution; Sleep disturbance; Sleep problem; Systematic review.

Publication types

Meta-Analysis
Systematic Review
Review

MeSH terms

Cross-Sectional Studies
Darkness
Humans
Light
Local Area Networks*
Sleep
Sleep Wake Disorders* / epidemiology
Sleep Wake Disorders* / etiology