Your Bedroom Light Could Be Quietly Weakening Your Heart, UK Biobank Study Warns

A landmark study of 11,071 UK Biobank participants published in the European Heart Journal has found that sleeping with even dim artificial light — as little as 3 lux — is associated with significant structural changes to the heart that could elevate cardiovascular disease risk.

Over three years, participants wore light-sensor wristbands for a week to measure nighttime exposure, then underwent cardiac MRI scans. Those exposed to more than 3 lux at night — roughly the...