- Exposure to artificial light while sleeping increased risk for weight gain and obesity, especially among women in this cohort study.
Why this matters
- Exposure to artificial light during sleep should be addressed in discussions about obesity prevention.
- Exposure to any artificial light at night was linked to increased baseline (prevalence ratios; 95% CIs):
- Obesity: 1.03 (1.02-1.03),
- Waist circumference: 1.12 (1.09-1.16),
- BMI: 1.03 (1.02-1.04),
- Waist-hip ratio: 1.04 (1.00-1.08), and
- Waist-height ratio: 1.07 (1.04-1.09).
- Compared with no light on, having on the TV or a light was linked to (relative risks; 95% CIs):
- Gaining 5 kg or more: 1.17 (1.08-1.27; Ptrend<.001>
- BMI increase ≥10%: 1.13 (1.02-1.26; Ptrend=.04), and
- Incidence overweight and obesity: 1.22 (1.06-1.40; Ptrend=.03) and 1.33 (1.13-1.57; Ptrend<.001 respectively.>
- The association was stronger for women with baseline normal weight or overweight than among women with obesity.
- Prospective analysis of data for 43,722 women ages 35-74 years, enrolled in US Sister Study, July 2003-March 2009.
- Funding: NIH.
- No way to track change in artificial light exposure over time, intensity, wavelength, other factors; exposures were self-reported.