Even Low Light Exposure During Sleep May Raise Your Risk of Heart Failure, AFib
New research indicates that even minimal light exposure during sleep can lead to changes in heart structure, potentially increasing the risk of cardiovascular issues such as heart failure and atrial fibrillation (AFib). The study highlights that light levels as low as 3 lux, approximately the brightness of moonlight, can negatively impact heart health over time.
Researchers analyzed data from over 11,000 participants in the UK Biobank, utilizing wrist devices to monitor light exposure while they slept. After a follow-up period of nearly three years, cardiac health was assessed using cardiovascular magnetic resonance imaging (MRI). The findings revealed that participants exposed to higher levels of nighttime light exhibited cardiac remodeling, characterized by slight thickening of the heart muscle and alterations in heart contraction. These changes could potentially lead to serious conditions like heart failure or AFib, according to the study.
Lead author Lu Qi, a professor at Tulane University, emphasized that this study is groundbreaking in linking nighttime light exposure to significant changes in heart structure and function. While previous research has suggested a correlation between nighttime light and cardiovascular disease risks, the specific effects on heart structure had remained unclear until now.
The study distinguished participants based on their nighttime light exposure, finding that those with light exposure above the 3 lux threshold had a 2.4% increase in left ventricular mass and a 1.5% increase in heart wall thickness compared to those with no exposure. Although these differences were small and did not immediately indicate cardiovascular disease, they could serve as early indicators of future health issues.
The findings align with earlier studies that found a connection between nighttime light exposure and increased risks of coronary artery disease, heart attack, and stroke. A 2025 study involving nearly 89,000 participants reported that individuals with higher nighttime light exposure faced significantly greater risks for various cardiovascular conditions.
Experts suggest that disruptions to the body’s circadian rhythm—our internal clock that regulates sleep and other bodily functions—may play a role in this association. Nighttime light can impair melatonin production, essential for quality sleep, which in turn may affect cardiovascular health.
To mitigate these risks, experts recommend optimizing sleep environments. Simple strategies include using blackout curtains to block external light, turning off electronic devices before bedtime, and employing dim, warm-colored nightlights when necessary. Maintaining a consistent sleep schedule and ensuring exposure to bright natural light during the day can also help reinforce the body’s natural rhythms.
While more research is needed to determine the direct impact of nighttime light exposure on heart health, adopting good sleep hygiene practices can be beneficial. Individuals are encouraged to focus on controllable cardiovascular risk factors, such as maintaining a heart-healthy diet, engaging in regular physical activity, and avoiding tobacco and excessive alcohol consumption. These lifestyle choices can contribute significantly to overall heart health.
