Want to Lower Stroke Risk? Make This One Change to Your Bedroom

Updated: Mar. 25, 2024

If you're not one of those people who needs every inch of light blocked out to sleep, you might be after you read what doctors in China have found...

Getting good sleep, seven to nine hours per night, is essential for maintaining good health. By now, most people know that the blue light emitted by our phones and devices can disrupt that sleep…but that’s not the only light that can hinder your necessary shut-eye. New research suggests if your bedroom isn’t dark enough due to outside light pollution, you could be putting your sleep—and your healthat risk.

A study published in the peer-reviewed journal Stroke on March 25, 2024 suggests that people who live within areas that are brightly lit, like cities, could be increasing their risk of stroke. The study followed 28,302 adults with an average age of 62 in a city in China from 2015 to 2021. The participants did not have any diagnosed cardiovascular disease at the onset of the study. They were followed for up to six years and evaluated for cerebrovascular disease, ischemic stroke, and hemorrhagic stroke. The level of light was mapped by satellite and correlated to where the people lived. It was then cross-referenced with hospital records and death certificates.

According to the study, people who lived with the highest level of nighttime light had a 43% increased risk of developing cerebrovascular disease. The lights evaluated were fluorescent, incandescent, and LED sources. “Our study suggests that higher levels of exposure to outdoor artificial light at night may be a risk factor for cerebrovascular disease,” said one of the study’s authors, Jian-Bing Wang, MD, PhD, a researcher associated with the Zhejiang University School of Medicine. “Therefore, we advise people, especially those living in urban areas, to consider reducing that exposure to protect themselves from its potential harmful impact.” 

The study’s authors highlight that this is a real problem for much of the world, citing that about 80% of the population lives in these “light-polluted environments.” Exposure to nighttime light has already been linked to higher rates of cardiovascular disease. This study now specifically links excess nighttime light to stroke risk. “Despite significant advances in reducing traditional cardiovascular risk factors such as smoking, obesity, and type 2 diabetes, it is important to consider environmental factors in our efforts to decrease the global burden of cardiovascular disease,” said Wang.

The fact that light can impact sleep quality isn’t new. The body’s circadian rhythm regulates the release of melatonin, and when any artificial light disrupts it, sleep can be erratic. “In the morning, we get sunlight that will suppress the release of melatonin. And at nighttime, as the sun goes down, melatonin is released,” Raj Dasgupta, MD, a fellow of the American Academy of Sleep Medicine and assistant professor of clinical medicine at the Keck School of Medicine at the University of Southern California previously explained to The Healthy by Reader’s Digest.

“Ideally, it’s better to sleep with no lights,” Dr. Dasgupta concluded. This is especially great advice if you live in an environment where artificial light disrupts your sleep. Investing in blackout shades and keeping your bedroom as dark as possible at night could improve your health—and maybe even lead to a longer life.