Recent research indicates that nighttime exposure to artificial light is linked to a higher risk of heart disease. A study led by Daniel Windred from the Flinders Health and Medical Research Institute revealed that prolonged exposure to nighttime light increases the risk of several cardiovascular diseases. The study analyzed data from approximately 90,000 participants from the UK Biobank. Participants in the study wore wrist devices capable of recording the intensity of light they received at night, distinguishing between artificial and natural light.
The light levels the participants were exposed to during the night were later matched with diagnoses of heart diseases, including coronary artery disease, heart attack, heart failure, arrhythmia, and stroke. Researchers suggested that the effect of light exposure is due to the disruption of the body's natural sleep-wake cycle, known as the circadian rhythm. The disruption can trigger metabolic and vascular changes, increasing the risk of heart diseases, including atherosclerosis and vulnerability to arrhythmias.
Participants with the highest nighttime light exposure had a higher risk of heart problems, including coronary artery disease, heart attack, heart failure, irregular heartbeat, and stroke. The risks were most pronounced among the top ten percent of those exposed to light at night.
Researchers considered factors affecting cardiovascular health in their analysis, including smoking, alcohol consumption, diet, sleep duration, physical activity, socioeconomic status, and genetic risk, yet the associations between nighttime light exposure and increased cardiovascular disease risk remained. Nighttime light exposure, whether from streetlights, phone screens, or TVs, disrupts circadian rhythms and is directly related to increased cardiac risks.
The circadian rhythm regulates internal processes, including sleep-wake cycles, blood pressure, heart rate, hormone secretion, and glucose metabolism, all of which are important for heart health. Increased tendency of blood to clot, known as hypercoagulability, has been associated with circadian rhythm disruption and is a possible biological mechanism linking nighttime light exposure to cardiovascular issues. Researchers hypothesize that there are multiple mechanisms through which light affects the heart.
Stronger connections were observed in younger participants for the risk of heart failure and arrhythmias. Young individuals in the high nighttime light exposure category were at greater risk of heart failure. Additionally, women with high night light exposure had a higher risk of heart failure and coronary heart disease, with stronger connections observed in women between light exposure and these risks.
Minimizing nighttime light exposure could be a simple and effective way to reduce the risk of cardiovascular diseases. Researchers recommended actions such as buying thick, light-blocking curtains, turning off electronic devices, and dimming lights before sleep to improve sleep quality. "Avoiding light at night may be a useful strategy to reduce the risk of cardiovascular diseases," the researchers suggested, according to T-Online.
Although the study did not prove a direct cause-and-effect relationship, the results suggest a correlation between nighttime light exposure and heart health issues. The researchers point out that the study is observational. The research has not yet been published in a peer-reviewed scientific journal, but the preprint version is available on the medRxiv platform, indicating the importance of further attention to this topic.
Researchers hope future studies will collect nighttime light exposure data over longer periods. They emphasize that further studies are necessary to establish the causality of the relationship between nighttime light exposure and cardiovascular diseases. The authors also suggest that urban and hospital planning consider lighting guidelines that respect circadian rhythms to reduce excessive exposure to nighttime light.
Written with the help of a news-analysis system.