Study Links Nighttime Light Exposure to Heart Changes

A large observational study has found that sleeping with even dim artificial light may lead to structural changes in the heart, potentially increasing the risk of cardiovascular disease. The research, published in the European Heart Journal, analyzed data from more than 11,000 UK Biobank participants who did not have existing heart conditions. Participants wore a wrist sensor for seven days to measure nighttime light exposure. Approximately three years later, they underwent cardiac MRI scans. Researchers compared individuals exposed to more than 3 lux of light during sleep with those in near-total darkness. Three lux is roughly equivalent to moonlight or light bleeding under a closed door. The study found that higher nighttime light exposure was associated with thicker walls in the heart's left ventricle, the main pumping chamber, and a reduction in the chamber's internal space. There was also a measurable decline in the heart muscle's ability to contract efficiently. Similar, though less pronounced, changes were observed in the right ventricle and left atrium. "Light pollution has emerged as a new risk factor for cardiovascular disease," said Dr.