Sex- and age-specific association between outdoor light at night and obesity in Chinese adults: A national cross-sectional study of 98,658 participants from 162 study sites

Front Endocrinol (Lausanne). 2023 Feb 20:14:1119658. doi: 10.3389/fendo.2023.1119658. eCollection 2023.

Abstract

Background: Exposure to light at night (LAN) is a potent disruptor of the circadian system. Whether LAN exposure exerts a sex- or age-specific influence on obesity needs investigation.

Objectives: To estimate the sex- and age-specific associations of exposure to outdoor LAN and obesity based on a national and cross-sectional survey.

Methods: The study included a nationally representative sample of 98,658 adults aged ≥ 18 years who had lived in their current residence for ≥ 6 months from 162 study sites across mainland China in 2010. Outdoor LAN exposure was estimated from satellite imaging data. General obesity was defined as body-mass index (BMI) ≥ 28 kg/m2 and central obesity was defined as waist circumference ≥ 90 cm in men and ≥ 85 cm in women. Linear and logistic regression models were used to examine the associations between LAN exposure and prevalent obesity in sex and age categories.

Results: A monotonically increasing association of outdoor LAN with BMI, waist circumference was observed in all sex and age categories, except for adults aged 18-39 years. Significant associations of LAN exposure with prevalent obesity were observed in each sex and age category, especially in men and older people. Per 1-quintile increase in LAN was associated with 14% increased odds of general obesity in men (odds ratio, OR=1.14, 95% confidence interval, CI=1.07-1.23) and 24% in adults aged ≥ 60 years (OR=1.24, 95% CI=1.14-1.35). Per 1-quintile increase in LAN was associated with 19% increased odds of central obesity in men (OR=1.19, 95% CI=1.11-1.26) and 26% in adults aged ≥ 60 years (OR=1.26, 95% CI=1.17-1.35).

Conclusions: Increased chronic outdoor LAN exposure was associated with increased prevalence of obesity in sex- and age- specific Chinese populations. Public health policies on reducing light pollution at night might be considered in obesity prevention.

Keywords: age; circadian system; obesity; outdoor light at night; sex difference.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Cross-Sectional Studies
  • East Asian People*
  • Female
  • Humans
  • Light* / adverse effects
  • Male
  • Middle Aged
  • Obesity* / epidemiology
  • Obesity* / etiology
  • Obesity, Abdominal* / epidemiology
  • Obesity, Abdominal* / etiology
  • Young Adult

Grants and funding

This work was supported by the grants from the Shanghai Jiading District Health Commission (2020-jdyxzdzk-01), the National Natural Science Foundation of China (82088102, 82022011, 82070880), the Shanghai Shenkang Hospital Development Center (SHDC2020CR1001A, SHDC2020CR3064B), the Ruijin Hospital (2018CR002), the Shanghai Clinical Research Center for Metabolic Diseases (19MC1910100), and the Innovative Research Team of High-Level Local Universities in Shanghai. Funding sources were not involved in the study design, data collection, analysis and interpretation, and report writing, and also did not have any restrictions on the publication of the article.