Artificial Light and Heart Health
Artificial light at night does more than disrupt sleep. It may be linked to changes in heart structure and function, potentially raising cardiovascular disease risk. Researchers at Tulane University found that greater light exposure at night correlates with negative cardiac remodeling and reduced heart function. These findings were published in the European Heart Journal on September 9. Cardiovascular diseases are the leading cause of death worldwide. In the U.S., one person dies every 34 seconds from these diseases, underscoring the need for preventive understanding.
The study analyzed data from over 11,000 UK Biobank participants. Devices on their wrists monitored nighttime light exposure for seven days. Participants underwent cardiovascular magnetic resonance imaging for heart structure and performance assessment.
Study Findings
Results showed that higher exposure to night light led to increased heart muscle mass and thicker heart walls, which can precede cardiovascular disease. Participants also exhibited signs of impaired heart function affecting both heart sides.
Dr. Lu Qi, study lead, emphasized that nighttime light impacts the heart partly by shortening sleep duration and quality. Nightlight is believed to disrupt the body’s circadian rhythm, the natural 24-hour clock governing multiple body systems.
Dr. Qi stated that turning off bedroom lights during sleep might benefit heart health.
Understanding Light Pollution
Light pollution involves excessive or unwanted artificial light. Common sources are streetlights, building lights, car headlights, electronic devices, and outdoor advertising.
Studies previously linked nighttime light exposure to obesity, hypertension, diabetes, and increased cardiovascular disease risk, attributing these conditions to impaired cardiac autonomic regulation, elevated systemic inflammation, and circadian rhythm disruption.
Martin Young, Professor of Medicine at the University of Alabama at Birmingham, explained that the circadian clock in each cell coordinates biological processes to occur at the right time of day. He highlighted that circadian clocks are sensitive to light, so night light exposure disrupts them. This disruption causes loss of synchronization among body cells and organs.
Young noted that lab studies show circadian clock disruption in heart cells blocks removal of damaged components during sleep and replacement with healthy ones before waking. Thus, sleep deprivation and circadian disruption lead to accumulation of damaged components and pathological heart growth.
Symptoms of Cardiovascular Diseases
Cardiovascular disease encompasses conditions affecting the heart and blood vessels. Symptoms vary by condition, but common warning signs include:
- Chest pain or discomfort
- Indigestion-like stomach pain
- Shortness of breath
- Throat tightness
- Dizziness or fainting
- Heart palpitations
- Extreme fatigue
- Leg, ankle, or foot swelling
Expert Opinions
Young asserted that this study’s importance is significant. Researchers understand that environmental factors and behaviors reducing sleep or impairing circadian rhythms increase cardiometabolic disease risks like obesity, diabetes, hypertension, stroke, and heart attacks. The findings stress the urgent need for improved understanding of nighttime light exposure’s role in disease development.
Young recommended reducing nighttime light exposure and suggested blocking blue light to protect circadian rhythms when reduction isn’t feasible. Additionally, resynchronizing clocks by light exposure, consuming breakfast, and being active in the morning helps align body clocks.
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