New research presented at the American Heart Association Scientific Sessions 2025 suggests that exposure to artificial light at night may increase stress-related brain activity and artery inflammation, potentially leading to heart disease.
The preliminary analysis, which will be presented later this month, included over 450 adults who did not have heart disease or cancer at the start of the study. All participants underwent a routine Positron Emission Tomography/Computed Tomography scan, which can be used to measure brain stress activity and arterial inflammation. Additionally, nighttime light and light pollution were measured at each participant’s home using an atlas of artificial night sky brightness. Participants completed their scans between 2005 and 2008, and their health records were reviewed through 2018. The goal of the study was to see whether artificial light exposure at night was linked to stress-related brain activity, artery inflammation, or major adverse cardiovascular events during the follow-up period.
The results showed that participants who were exposed to more artificial light at night had higher stress-related brain activity, higher arterial inflammation, and a greater risk of adverse cardiovascular events. More light exposure at night significantly increased the risk of heart disease; each standard deviation increase in light exposure correlated with a 35% increase in the risk of heart disease over a five-year follow-up period and a 22% increase in risk over a ten-year follow-up period. Effects were even more pronounced in areas with other factors that may increase stress, such as high traffic noise or low average income.
The investigators noted that environmental factors that increase stress, such as air pollution and noise pollution, are known to increase the risk of heart disease. This study further shows that light pollution may also increase stress-related brain activity and the risk of heart disease. The novel results of this study suggest that light pollution is a public health concern that should be addressed, and that individuals living in highly light-polluted areas should consider mitigation strategies such as blackout curtains.
Sources: AHA, Science Daily