Limiting Nighttime Light Can Boost Heart Health

Quick Smiles:

• New research links nighttime artificial light to stress and heart health risks.
• Simple changes like darkening bedrooms may help protect the heart.
• Experts recommend city and lifestyle updates to reduce light exposure.

Modern life often means artificial light outside and inside our homes at night, but a new study suggests these sources may add stress to our brains and increase risk for heart disease.

Researchers presented findings at the American Heart Association’s Scientific Sessions 2025, showing a connection between higher levels of nighttime light in the environment and increased stress activity in the brain, blood vessel inflammation, and heart event risk.

The study, led by Dr. Shady Abohashem from Massachusetts General Hospital, reviewed brain scans and satellite images to explore how exposure to city lights at night could impact heart health.

“We know that environmental factors, such as air and noise pollution, can lead to heart disease by affecting our nerves and blood vessels through stress. Light pollution is very common; however, we don’t know much about how it affects the heart,” said Dr. Abohashem.

Over 450 adults without heart disease or active cancer received combined PET/CT imaging, which helped reveal stress responses in the brain and inflammation in arteries.

The analysis showed that people exposed to higher levels of artificial light at night had more brain stress, increased vessel inflammation, and a greater risk for heart events over five and ten years.

Importantly, these risks remained even after considering traditional risks and socio-environmental factors such as noise and income.

“We found a nearly linear relationship between nighttime light and heart disease: the more night-light exposure, the higher the risk. Even modest increases in night-time light were linked with higher brain and artery stress,” Abohashem explained. “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.”

Limiting indoor lights and reducing screens before bed, as well as using shielded or motion-sensitive outdoor lighting, are some strategies the researchers recommend to help protect heart health.

Dr. Julio Fernandez-Mendoza of Pennsylvania State University 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.”

While the study’s observational design means it cannot prove cause-and-effect, experts say the results support taking simple steps at home and in cities to reduce nighttime light for a healthier heart.

Small changes to your environment can bring big benefits to your well-being—share this insight with someone you care about!

Source