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ADELAIDE, Australia — People at risk for Type 2 diabetes are often told to take preventative measures to control their blood sugar levels. Exercising regularly, sleeping eight hours a night, and avoiding fast food are typical recommendations for people with prediabetes. Now, a new study finds that another recommendation should be to avoid bright lights at night.

Researchers in Australia, publishing their work in The Lancet Regional Health – Europe, found an unusual link between nighttime light exposure and an increased risk for Type 2 diabetes.

“The results showed that exposure to brighter light at night is associated with a higher risk of developing diabetes, with a dose-dependent relationship between light exposure and risk,” says Andrew Phillips, an associate professor from Flinders University College of Medicine and Public Health, in a media release.

Type 2 diabetes is a chronic health condition in which the body cannot properly use insulin. Insulin is needed to help move glucose into cells, which then converts the glucose into energy. Without insulin, the body has high blood sugar levels, and cells are deprived of energy. Once a person develops Type 2 diabetes, it’s extremely difficult to push the condition into remission.

diabetes
Type 2 diabetes is a chronic health condition in which the body cannot properly use insulin. (Credit: Artem Podrez from Pexels)

Methodology

The research team used modeling data to investigate the relationship between exposure to bright lights and diabetes risk. They analyzed personal light exposure patterns from approximately 85,000 people and 13 million hours of light sensor data. 

People who did not have Type 2 diabetes wore a tracker on their wrists to collect light levels during the day and night. These participants were then tracked for nine years to see if they later developed Type 2 diabetes.

Results

People who were exposed to bright lights between 12:30 a.m. and 6 a.m. had a higher risk of Type 2 diabetes. This link remained regardless of how much light people were exposed to during the daytime.

The link between nighttime light exposure and Type 2 diabetes remained even when the authors accounted for lifestyle habits, sleep patterns, shift work, diet, and mental health. According to the authors, bright night lights raise a person’s risk of Type 2 diabetes by disrupting their circadian rhythms

Circadian rhythms are the internal clock that tells the body when it’s time to feel awake or tired, aligning with the 24-hour cycle of light and darkness. Disrupting this biological clock disturbs the normal rhythm of other bodily processes, such as glucose metabolism and insulin secretion levels, which regulate blood sugar.

Discussion and Takeaways

The study findings suggest bright lights can disrupt normal bodily processes. With this in mind, Phillips advises turning your lights off at night before you go to sleep.

“The results showed that exposure to brighter light at night is associated with a higher risk of developing diabetes, with a dose-dependent relationship between light exposure and risk,” Phillips concludes.

“Our findings suggest that reducing your light exposure at night and maintaining a dark environment may be an easy and cheap way to prevent or delay the development of diabetes.”

About Jocelyn Solis-Moreira

Jocelyn is a New York-based science journalist whose work has appeared in Discover Magazine, Health, and Live Science, among other publications. She holds a Master's of Science in Psychology with a concentration in behavioral neuroscience and a Bachelor's of Science in integrative neuroscience from Binghamton University. Jocelyn has reported on several medical and science topics ranging from coronavirus news to the latest findings in women's health.

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