Exposure to even minimal light during sleep can alter the shape and function of heart muscles, increasing the risk of future heart disease, a recent study has indicated, reports BritPanorama.
“Light pollution has emerged as a new risk factor for cardiovascular disease,” said Dr. Lu Qi, senior study author and director of the Tulane University Obesity Research Center in New Orleans. The study highlights a correlation between nighttime light exposure and cardiovascular health, emphasizing the potential for light reduction as a preventive measure.
For optimal sleep quality, experts recommend that the bedroom should ideally have light levels below 1 lux, substantially lower than 3 lux, which is akin to the illumination from a closed door. The study monitored 11,000 participants from the UK Biobank, revealing that those exposed to over 3 lux had significant thickening of heart muscle walls, impairing the heart’s pumping efficiency.
The degree of harm escalated with increased light exposure, including sources such as smartphone glow or external light pollution. This transformation of heart muscle, termed cardiac “remodeling,” can lead to early signs of heart dysfunction.
Thicker heart muscles may lead to heart failure
Published in the European Heart Journal, the research involved participants who wore wrist sensors for a week to track light exposure, followed by a cardiovascular MRI after three years to evaluate heart health. Results indicated that individuals exposed to light while sleeping exhibited thickened left ventricular walls and reduced muscle flexibility during heartbeats, suggesting potential early indicators of heart failure.
Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver, noted, “We don’t want the heart muscle to get thick. We don’t want the heart muscle to get stiff.” He pointed to the detrimental effects of excess light exposure on heart health, underscoring the importance of quality sleep.
The study also found a direct link between light exposure at night and reduced sleep duration, attributing 24% to 49% of cardiovascular risk to shortened sleep caused by nighttime light. Dr. Qi suggests that light exposure could disrupt other cardiovascular risk factors, impacting elements such as stress and biological changes in blood pressure.
Despite its findings, the study faced critiques regarding its methodology. Karl Lawrence from King’s College London highlighted limitations, including the short duration of light exposure assessment and the potential for inaccurate estimations of light received by the eye. He argued that further research is necessary to establish causal relationships between nighttime light exposure and heart health.
Blocking light at night
Experts recommend practical steps to mitigate light exposure in the bedroom, such as using heavy drapes or inexpensive blackout curtains to create a suitably dark environment. They also advise turning off hallway lights and using light-blocking materials to minimize light intrusion during the night.
In terms of bedside lighting, they recommend bulbs that emit warm, dim light to facilitate better sleep conditions. A dimly lit bedside lamp can significantly contribute to creating a conducive environment for sleep.
As awareness of the relationship between light exposure and cardiovascular health grows, ongoing inquiries into effective prevention strategies will undoubtedly shape future guidelines for promoting heart health.
