Overview
- A European Heart Journal analysis published in September 2026 measured night light with wrist sensors in about 11,000 UK Biobank participants and then used cardiac MRI roughly three years later to test for structural changes.
- Exposure above roughly 3 lux was associated with subtle cardiac remodelling, including about 2.4% greater left ventricular mass, 1.5% thicker walls, and 1.9% lower myocardial contraction fraction.
- Larger follow-up of roughly 73,000 people over up to a decade found higher night light linked to greater risks of heart failure, heart attack, stroke and atrial fibrillation after adjustment for other factors.
- Shorter sleep explained about 24%–49% of the link, and authors point to circadian disruption, melatonin suppression and autonomic changes as plausible additional pathways.
- The study’s limits include a one-week wrist-light snapshot, no information on light wavelength or eye exposure, and a mostly White UK sample, so experts recommend simple bedroom fixes like blackout curtains and dim warm lights while further replication and trials are pursued.