Association between outdoor artificial light at night and sleep duration among older adults in China: A cross-sectional study

Kejia Hu, Wanlu Li, Yunquan Zhang, Huashuai Chen, Chen Bai, Zhenchun Yang, Thiess Lorenz, Keyang Liu, Kokoro Shirai, Jinglu Song, Qi Zhao, Yali Zhao, Junfeng (Jim) Zhang, Jing Wei, Jiahao Pan, Jin Qi, Tingting Ye, Yi Zeng*, Yao Yao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Background: Light after dusk disrupts the circadian rhythms and shifts the timing of sleep later; but it is unknown whether outdoor artificial light at night (ALAN) affects sleep quality. This study aimed to explore the association between residential outdoor ALAN and sleep duration in a nationally representative sample of Chinese older adults. Methods: We examined the cross-sectional associations of outdoor ALAN with self-reported sleep duration in 13,474 older adults participating in the 2017–2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Outdoor ALAN exposure was estimated at the residence level using satellite images. We applied generalized linear mixed models to investigate the association between ALAN exposure and sleep duration. We performed stratified analyses by age, sex, education, and household income levels. Moreover, we used multi-level logistic regression models to investigate the effects of ALAN on the short sleep duration (≤6 h) and the long sleep duration (>8 h), respectively, in reference to sleep for >6–8 h per day. Results: We found a significant association between outdoor ALAN intensity and sleep duration. The highest quartile of ALAN was associated with 17.04 (95% CI: 9.42–24.78) fewer minutes of sleep as compared to the lowest quartile. The reductions in sleep duration per quartile change in ALAN were greater in the young old (≥65–85 years) and in those with higher levels of education, and those with higher household income, respectively. We did not detect a sex difference. In addition, those in the highest quartile of ALAN were more likely to report a 25% (95% CI: 10%–42%) increase in short sleep (<6 h), and a 21% (95% CI: 9%–31%) decrease in long sleep (>8 h). Conclusions: Increasing outdoor nighttime light intensity surrounding residences was associated with shorter sleep duration in older residents in China. This finding implies the importance of urban outdoor artificial light management as a potential means to lower the public health burden of sleep disorders.

Original languageEnglish
Article number113343
JournalEnvironmental Research
Volume212
DOIs
Publication statusPublished - Sept 2022

Keywords

  • ALAN
  • China
  • Nighttime light
  • Outdoor light
  • Sleep
  • Sleep duration

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