Nighttime Light Exposure Could Harm Heart Health, Study Suggests

You may already be eating well, staying active and keeping your blood pressure in check, yet still overlook one important heart risk.

That risk shows up while you sleep, and there are straightforward ways to reduce it.

Start by taking a closer look at your bedroom.

Heart Health Tip of the Day: Limit Light While You Sleep

Researchers told the European Society of Cardiology that exposure to light at night during sleep is associated with “adverse cardiac remodeling,” meaning changes in the heart’s shape and function that are often seen with long-term stress or injury.

“It’s our body’s way of adapting to that stress, but ultimately it weakens the heart and can lead to heart failure,” Dr. Lu Qi, a professor at Tulane University’s School of Public Health and Tropical Medicine, said in a statement. He is a co-author of a recent study on the topic.

“Light pollution has emerged as a new risk factor for cardiovascular disease,” he added.

Doctors have previously told the National Heart, Lung and Blood Institute that the connection between nighttime light and cardiovascular disease has often been overlooked.

Why It Matters

In a study published in the European Heart Journal, Qi and his colleagues reported that greater exposure to light during the night was tied to a decline in heart function, including thickening of the left ventricle wall that reduced the chamber’s interior space.

The European Society of Cardiology said the heart muscle also appeared less able to flex during each beat, which can be an early sign of heart dysfunction.

Changes were also seen in the heart’s right ventricles and left atria.

The findings were based on data from more than 11,000 people who wore a wrist sensor for seven nights to measure light exposure during sleep, then underwent a cardiac MRI three years later.

Researchers said artificial light at night acts as a “biologically active environmental stressor” that suppresses melatonin, disrupts sleep cycles, changes metabolic and inflammatory rhythms, and “ultimately affects nearly every cardiovascular cell type.”

“The light in our bedrooms deserves consideration as a cardiovascular risk factor, alongside smoking, hypertension, and physical inactivity,” they warned. “Darkness deserves recognition as a vital sign, as essential to cardiovascular health as blood pressure control and clean air.”

How to Get Started

To help protect your heart, sleep in complete darkness when possible. Close blinds and switch off lights and any devices that emit light.

If some light still gets in, consider blackout curtains or an eye mask. That may be especially helpful for people who work night shifts and sleep during the day.

“Reduction of nighttime light exposure should be considered as one of the potential strategies for preventing heart disease,” Qi said.