Artificial Night Light Linked to Heart Structure Changes

Artificial light at night disrupts more than sleep. A new study suggests it may change the heart’s structure and function, increasing cardiovascular disease risks. Researchers at Tulane University linked greater nighttime light exposure to signs of adverse cardiac remodeling and reduced heart function. These findings were published in the European Heart Journal on September 9.

Cardiovascular diseases are the top cause of death worldwide, with one death every 34 seconds from cardiovascular disease in the U.S. This emphasizes the importance of advancing prevention knowledge.

Study Details

The study analyzed data from over 11,000 UK Biobank participants. They wore wrist devices to monitor nighttime light exposure over seven days. Participants then underwent cardiovascular magnetic resonance (CMR) imaging to assess heart structure and function.

The researchers discovered that increased nighttime light exposure resulted in greater heart muscle mass and thicker heart walls. These changes can lead to cardiovascular disease. Impaired heart function was also noted in both heart sides.

Dr. Lu Qi, study lead and director of the Tulane University Obesity Research Center, explained that nighttime light exposure might affect heart health by shortening sleep duration and quality. Nighttime light can disrupt the body’s circadian rhythm, which influences various bodily systems.

Dr. Qi concluded that bedroom light is important for cardiovascular health. Turning off lights during sleep could benefit heart health.

Light Pollution Explained

Light pollution refers to excessive artificial light in the environment. Common sources include streetlights, building lights, vehicle headlights, electronic devices, and outdoor advertising.

Previous studies link nighttime light exposure to obesity, hypertension, diabetes, and higher cardiovascular disease risk. This is often attributed to disrupted cardiac autonomic regulation, systemic inflammation, and circadian rhythm interference.

Martin Young, a professor of medicine at the University of Alabama at Birmingham, discussed this with Newsweek. He stated that each cell has a molecular circadian clock ensuring processes occur at the correct time. Circadian clocks are highly sensitive to environmental factors, especially light. Light at night disrupts these clocks, leading to a disconnect between cells and organs.

Young noted that lab studies show circadian disruption in heart cells prevents removing damaged components during sleep and replacing them with functional ones by morning. Sleep deprivation and circadian disruption prevent normal cycles, causing damaged cellular components to accumulate and the heart to grow pathologically.

Symptoms of Cardiovascular Diseases

Cardiovascular disease includes conditions affecting the heart and blood vessels. Symptoms vary based on the exact condition.

• Chest pain or discomfort
• Stomach pain resembling indigestion
• Shortness of breath
• Throat tightness
• Dizziness or fainting
• Heart palpitations
• Extreme fatigue
• Leg, ankle, or foot swelling

Expert Opinions

Young emphasized the study’s significance, noting the known risks that environmental factors and behaviors pose to sleep and circadian rhythms. These risks increase the chance of developing cardiometabolic diseases.

Given the findings, reducing nighttime light exposure is advisable. If unavoidable, blocking blue light wavelengths could be one alternative.

Young suggested additional ways to ‘resynchronize’ clocks, such as morning exposure to light, eating a good breakfast, and physical activity.

Reference

Jin Dai, Wen Dai, Yoriko Heianza, Lu Qi, (2026) Nighttime light exposure and cardiac structure and function, European Heart Journal. https://doi.org/10.1093/eurheartj/ehag563

Update 9/11/26, 11:24 a.m. ET: This article was updated with additional information.

Contact Newsweek editors on this story: Marc Vargas and Emma Lee-Sang