Too much light at night might be doing more than keeping you awake—it could be putting extra stress on your brain and heart.Researchers found that people exposed to more artificial light…from streetlamps to phone screens… showed greater brain stress activity, blood vessel inflammation and a higher risk of major heart events over time.The study included 466 healthy adults who had detailed brain and artery scans and were then followed for nearly a decade.The results showed that 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.Scientists say nighttime light pollution may overstimulate the brain’s stress response, triggering inflammation that damages blood vessels and raises the risk for heart attacks and strokes.While the study can’t prove cause and effect, the researchers say the pattern was clear—the more light at night, the greater the risk.Simple steps, like dimming indoor lights, using blackout curtains and avoiding screens before bed, can help protect your sleep—and your heart.These findings will be presented at the American Heart Association’s Scientific Sessions 2025 (Nov. 7-10, 2025) and are considered preliminary until published as full manuscripts in a peer-reviewed scientific journal. Author Associations: Massachusetts General Hospital, Harvard Medical School .Sign up for our weekly HealthDay newsletter