Nighttime Light and Heart Health

Higher exposure to artificial light at night correlated with heightened stress activity in the brain, inflammation in the arteries, and a greater likelihood of heart disease in a small study of adults in Boston. Researchers reported that light pollution at night appeared to influence cardiovascular health, suggesting it is a modifiable environmental factor in communities with elevated nighttime brightness.

A preliminary analysis presented at the American Heart Association’s Scientific Sessions 2025 found that greater artificial light at night correlated with increased brain stress signals, inflamed blood vessels, and higher heart disease risk. The conference, featuring new developments, research, and practice updates in cardiovascular science, will take place Nov.7-10 in New Orleans.

Investigators described artificial light at night, often called nighttime light pollution, as nearly worldwide in modern urban settings. This first-of-its-kind work combined brain imaging and satellite measurements to outline a biological pathway that may connect nighttime brightness with cardiovascular risk.

“We no 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 study senior author Shady Abohashem, M.D., M.P.H., head of cardiac PET/CT imaging trials at Massachusetts General Hospital and an instructor at harvard Medical School in Boston.

All participants underwent the same combined Positron Emission Tomography/Computed Tomography (PET/CT) scan. This study of 450 adults only included subjects without heart disease and no active cancer. “This is a routine imaging test at my hospital,” Abohashem said. “The CT portion provides detailed anatomy, while the PET portion reveals metabolic activity in tissues. Using both imaging techniques together allows for the measurement of brain stress activity and arterial inflammation in a single scan.”

Key Results: Higher Light Exposure, Higher Risk

• People exposed to higher levels of artificial light at night had higher brain stress activity, blood vessel inflammation, and a higher risk of major heart events.Cardiologists blinded to participant information evaluated this data from medical records.
• The greater the artificial night light exposure,the higher the risk of heart disease development. Each standard deviation increase in light exposure was associated with approximately 35% and 22% increased risk of heart disease over five- and 10-year follow-up periods, respectively. These associations remained after accounting for traditional risk factors and other socio-environmental exposures like noise pollution and socioeconomic status.
• Heart risks were higher among participants who lived in areas with additional social or environmental stress, such as high traffic noise or lower neighborhood income.
• Over a 10-year follow-up period,17% of participants experienced major heart conditions.

Stress Pathways and Vessel Inflammation

“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 said. “When the brain perceives stress,it activates… “