Association Between Exposure to Outdoor Artificial Light at Night and Sleep Disorders Among Children in China

Importance

Healthy sleep has an important role in the physical and mental health of children. However, few studies have investigated the association between outdoor artificial light at night (ALAN) and sleep disorders in children.

Objective

To explore the associations between outdoor ALAN exposure and sleep disorders in children.

Design, Setting, and Participants

This population-based cross-sectional study, part of the National Chinese Children Health Study, was conducted from April 1, 2012, to June 30, 2013, in the first stage and from May 1, 2016, to May 31, 2018, in the second stage in 55 districts of 14 cities in China. This analysis included 201 994 children and adolescents aged 2 to 18 years. Data were analyzed from February 20 to March 21, 2022.

Exposures

Outdoor ALAN exposure (in nanowatts per centimeters squared per steradian) within 500 m of each participant’s residential address obtained from the satellite imagery data, with a resolution of approximately 500 m.

Main Outcomes and Measures

Sleep disorders were measured by the Chinese version of the Sleep Disturbance Scale for Children. Generalized linear mixed models were used to estimate the associations of outdoor ALAN with sleep scores and sleep disorders.

Results

The study included 201 994 children and adolescents (mean [SD] age, 11.3 [3.2] years; 106 378 boys [52.7%]), 7166 (3.5%) of whom had sleep disorder symptoms. Outdoor ALAN exposure of study participants ranged from 0.02 to 113.48 nW/cm²/sr. Compared with the lowest quintile (Q1) of outdoor ALAN exposure, higher quintiles of exposure (Q2-Q5) were associated with an increase in total sleep scores of 0.81 (95% CI, 0.66-0.96) in Q2, 0.83 (95% CI, 0.68-0.97) in Q3, 0.62 (95% CI, 0.46-0.77) in Q4, and 0.53 (95% CI, 0.36-0.70) in Q5. Higher quintiles of exposure were also associated with odds ratios for sleep disorder of 1.34 (95% CI, 1.23-1.45) in Q2, 1.43 (95% CI, 1.32-1.55) in Q3, 1.31 (95% CI, 1.21-1.43) in Q4, and 1.25 (95% CI, 1.14-1.38) in Q5. Similar associations were observed for sleep disorder subtypes. In addition, greater effect estimates were found among children younger than 12 years.

Conclusions and Relevance

The findings of this cross-sectional study suggest that sleep disorders are more prevalent among children residing in areas with high levels of outdoor ALAN and the associations are generally stronger in children younger than 12 years. These findings further suggest that effective control of outdoor ALAN may be an important measure for improving the quality of children’s sleep.