Park YMM, et al. - In this baseline and prospective analysis involving 43,722 women aged 35-74 years from the Sister Study, researchers ascertained if exposure of artificial light at night (ALAN) while sleeping is correlated with the prevalence and risk of obesity. During sleep, they found that ALAN exposure may be related to increased weight, suggesting that nighttime exposure to artificial light should be addressed in discussions on obesity prevention.

Methods

• This investigation included women with no history of cancer or cardiovascular disease who were not shift workers, daytime sleepers, or pregnant at baseline.
• Baseline prevalent obesity was based on measured general obesity (body mass index [BMI] ≥ 30.0) and central obesity (waist circumference [WC] ≥ 88 cm, waist-to-hip ratio [WHR] ≥ 0.85, or waist-to-height ratio [WHtR] ≥ 0.5).
• In order to assess overweight and obesity incidents, self-reported BMI was contrasted with self-reported follow-up BMI (mean [SD] follow-up, 5.7 [1.0] years).
• To estimate multivariable-adjusted prevalence ratios (PRs) and relative risks (RRs) with 95% CIs for prevalent and incident obesity, generalized log-linear models with robust error variance were used.

Results

• ALAN exposure while sleeping was positively linked to a higher prevalence of obesity at baseline, as measured by BMI, WC, WHR, and WHtR, after adjusting for confounding factors, with P < 0.001 for trend for each measure.
• Incident obesity was also correlated with any ALAN exposure during sleep (RR: 1.19; 95% CI: 1.06-1.34).
• Compared with no ALAN, sleeping with a television or a light on in the room was related to gaining 5 kg or more, a BMI increase of 10% or, incident overweight, and incident obesity.
• Sensitivity analyses and additional multivariable analyses—including potential mediators like sleep duration and quality, diet, and physical activity—supported the results.