Light at Night Linked to Obesity, Diabetes and Hypertension

Light at night (LAN) has been associated with negative health consequences and metabolic risk factors. Little is known about the prevalence of LAN in older adults in the U.S. and its association with cardiovascular disease (CVD) risk factors. 

In a recently published study, researchers found that any amount of light while sleeping at night was associated with obesity, hypertension, and diabetes when compared to adults who were not exposed to any light during the night. The results were published in the journal Sleep. 

More than Half of Participants Were Exposed to Light During the Night

The study participants were enrolled in the Chicago Heart Association Detection Project in Industry (CHA), a public health program and epidemiologic study conducted in 1967-1973 to identify high-risk adults for heart diseases in workplaces. 

During a previous study, called Chicago Healthy Aging Study, with 1,395 survivors of the original CHA study, participants underwent examinations of blood pressure, weight, height, cholesterol, glucose and other known factors for cardiovascular disease, and wore an actigraphy device for 7 days and filled out a sleep diary. The device used had the capacity to measure light exposure.

Overall, the researchers found that light at night was associated with a higher prevalence of obesity, diabetes, and hypertension, but not with hypercholesterolemia. 

The researchers were surprised to find out that less than half of the 552 study participants consistently had a five-hour period of complete darkness per day.    

A previously published study by Ivy C. Manson, et al found similar results regarding the potential side effects of light at night in relation with cardiovascular health. This study adds to the current knowledge of how light during sleep can have a potential negative effect in our cardiovascular health. 


Minjee Kim, Thanh-Huyen Vu, Matthew B Maas, Rosemary I Braun, Michael S Wolf, Till Roenneberg, Martha L Daviglus, Kathryn J Reid, Phyllis C Zee. Light at night in older age is associated with obesity, diabetes, and hypertension. Sleep, 2022; DOI: 10.1093/sleep/zsac130 

Northwestern University. “Light during sleep in older adults linked to obesity, diabetes, high blood pressure: Night lights, TV left on, smart phones linked to significantly higher disease rates, study finds.” ScienceDaily. ScienceDaily, 27 June 2022. <>. 

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