Tulane University study links nighttime light to heart structural changes

A study published in the European Heart Journal suggests that nighttime light exposure is associated with adverse changes in heart structure and function. Led by Professor Lu Qi of Tulane University, researchers analyzed data from 11,071 UK Biobank participants who wore light-sensing wrist devices for seven days. Approximately three years later, participants underwent cardiac MRI scans to assess physical changes.

The findings indicate that individuals exposed to more than 3 lux of light during the night—a level comparable to moonlight or light leaking under a door—showed signs of cardiac remodeling. Specifically, the high-exposure group exhibited a 2.4% increase in left ventricular mass and a 1.5% increase in wall thickness. Additionally, researchers noted a 1.9% decrease in myocardial contractile fraction and reduced ability for the heart muscle to relax.

While the study identifies a strong association between light exposure and these subclinical changes, researchers noted it is observational and does not prove direct causation. The study suggests that reducing nighttime light exposure, such as by using blackout curtains or limiting screen use, could be a potential strategy for preventing cardiovascular disease.