Turning off bedroom light sources could help stave off weight gain



Obesity is a significant public health challenge and efforts to address it by promoting healthy diets and exercise have achieved little success. Identifying other factors that contribute to obesity is therefore of great importance.


IRP researchers led by Dale P. Sandler, Ph.D., analyzed comprehensive questionnaire and clinical data from more than 43,000 women participating in The Sister Study, a long-term study of risk factors for breast cancer. The IRP team determined that women who slept at night in rooms with televisions or other light sources on were more likely to have been overweight or obese at the start of the study and were more likely to gain weight or become obese during follow-up. Differences in sleep quality and duration, calorie intake, and physical activity could not explain the connection between exposure to artificial light at night and weight gain.


The study suggests that nighttime exposure to artificial light sources, which can disturb the sleep-wake cycle by affecting melatonin levels, may be an important contributing factor to weight gain. Consequently, along with eating a healthy diet and maintaining a physically active lifestyle, turning off sources of artificial light at bedtime may be a simple thing women can do to reduce their chances of gaining weight.


Park YM, White AJ, Jackson CL, Weinberg CR, Sandler DP. (2019) Association of exposure to artificial light at night while sleeping with risk of obesity in women. JAMA Intern. Med. Jun 10;179(8):1061-1071. doi: 10.1001/jamainternmed.2019.0571.

Sandler DP, Hodgson ME, Deming-Halverson SL, Juras PS, D’Aloisio AD, Suarez L, Kleeberger C, Shore DL, Bilhorn A, DeRoo LA, Taylor JA, Weinberg CR for the Sister Study team. (2017). The Sister Study: Baseline methods and participant characteristics. Environ. Health Perspect. Dec. 20;125(12):127003. doi: 10.1289/EHP1923.

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This page was last updated on Friday, June 9, 2023