• Posted November 3, 2025

Light Pollution Harming Heart Health, Study Says

The bright lights of the big city might seem dazzling, but they can be hard on your heart health, a new study says.

People exposed to high levels of artificial light have an increasingly higher risk of heart disease, researchers are scheduled to report at a Nov. 10 meeting of the American Heart Association in New Orleans.

Higher exposure to artificial light at night was associated with a 35% increased risk of heart disease within five years, and a 22% increased risk over 10 years, researchers found.

“We found a nearly linear relationship between nighttime light and heart disease: the more night-light exposure, the higher the risk,” senior researcher Dr. Shady Abohashem, head of PET/CT cardiac imaging trials at Massachusetts General Hospital in Boston, said in a news release.

For the new study, researchers analyzed the health of 466 adults with an average age of 55 who’d undergone a PET or CT scan at Massachusetts General Hospital between 2005 and 2008.

The team compared the participants’ health and brain scans to their exposure to artificial light, based on their home address.

Results showed that higher levels of artificial light caused brain stress activity and blood vessel inflammation.

“Even modest increases in night-time light were linked with higher brain and artery stress,” Abohashem said. “When the brain perceives stress, it activates signals that can trigger an immune response and inflame the blood vessels. Over time, this process can contribute to hardening of the arteries and increase the risk of heart attack and stroke.”

Over a decade, 17% of the people developed a major heart condition. Their light exposure was associated with risk of heart disease, even after accounting for other risk factors.

Heart risks were even higher among people who lived in areas with high traffic noise, lower neighborhood income or other environmental factors that can add to stress, researchers said.

To counter these ill effects, “people can limit indoor nighttime light, keeping bedrooms dark and avoiding screens such as TVs and personal electronic devices before bed,” Abohashem said.

Cities also might improve folks’ health by reducing unnecessary outdoor lighting, shielding street lamps, or using motion-sensitive lights, researchers said.

“These findings are novel and add to the evidence suggesting that reducing exposure to excessive artificial light at night is a public health concern,” Julio Fernandez-Mendoza, an American Heart Association spokesman, said in a news release.

“We know too much exposure to artificial light at night can harm your health, particularly increasing the risk of heart disease. However, we did not know how this harm happened,” said Fernandez-Mendoza, director of behavioral sleep medicine at Pennsylvania State University College of Medicine, who was not involved in the study.

“This study has investigated one of several possible causes, which is how our brains respond to stress,” he explained. “This response seems to play a big role in linking artificial light at night to heart disease.”

Researchers next plan to see whether reducing nighttime light exposure might improve people’s heart health.

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

James Madison University has more on light pollution.

SOURCE: American Heart Association, news release, Nov. 3, 2025