Even Dim Nighttime Light May Harm Heart Muscle Structure, Study Finds
A new study links exposure to low levels of light during sleep with thickening of heart muscle walls, potentially raising cardiovascular risk.
In a study published in the European Heart Journal, scientists examined sleep-related light exposure in more than 11,000 adults without prior heart disease, using wrist-mounted sensors for a week. Participants whose bedrooms received more than 3 lux of light—equivalent to bright moonlight—developed thicker left-ventricle walls and diminished chamber space, impairing the heart's pumping ability. Follow-up cardiac MRI scans three years later confirmed these structural changes, which also appeared in two additional chambers.
The researchers estimate that reduced sleep time accounts for up to half of the observed risk, while other factors like stress may contribute. Critics note the short monitoring period and the indirect measurement of eye-level light as limitations. Health professionals recommend dark sleeping environments, using heavy curtains, light-blocking strips, or sleep masks, and opting for low-intensity, warm-colored nightlights if needed.
How this was covered
- Left-leaning outlets covered this 9h later
