Khaberni - A new study has shown a correlation between high levels of artificial light at night and increased brain activity related to stress, arterial inflammation, and an increased risk of heart disease.
The study was conducted by researchers at Harvard Medical School in the United States, and the preliminary study results will be presented at the 2025 American Heart Association's Scientific Sessions, which will be held from November 7 to 10 in New Orleans, United States, and was reported on by the website EurekAlert.
Artificial light at night, or night-time light pollution, is an almost universal feature of modern cities, and this study reviewed brain scans and satellite images to demonstrate a biological pathway linking exposure to night-time light to heart disease.
Dr. Shady Abu Hashem, a co-researcher in the study, who holds a Master of Public Health and is the head of positron emission tomography/computed tomography heart imaging trials at Massachusetts General Hospital, and a lecturer at Harvard Medical School in Boston, said: "We know that environmental factors, such as air pollution and noise, can lead to heart disease by affecting our nerves and blood vessels as a result of stress. Light pollution is very common, yet we don't know much about how it affects the heart."
Artificial Brightness
This study included 450 adults who did not suffer from heart disease or any active cancer, and all participants underwent the same positron emission tomography/computed tomography (PET/CT) scan.
Abu Hashem said: "This is a routine imaging test at my hospital. The computed tomography part provides detailed anatomy, while the positron emission part detects metabolic activity in tissues. Using both imaging techniques together allows us to measure brain stress activity and arterial inflammation in a single examination."
Data on light exposure was obtained from the 2016 New World Atlas of Artificial Night Sky Brightness, which defines artificial brightness as the brightness of the night sky at ground level, attributed exclusively to human-generated light sources, excluding natural sources like starlight, atmospheric glow, and moonlight.
The amount of night-time light at each person’s home, as well as brain stress signals and signs of arterial inflammation, were measured in the scans.
Individuals exposed to higher levels of artificial light at night had higher brain stress activity, vascular inflammation, and a higher risk of severe heart attacks.
Night Light and Heart Disease
This information was gathered from medical records, and evaluated by two cardiologists who were unaware of any information that might influence their decisions.
The more one is exposed to artificial light at night, the greater the risk of heart disease. Additionally, the risks of heart disease were higher among participants living in areas with additional social or environmental stresses, such as high traffic noise.
Abu Hashem said: "We found a relationship between night-time light and heart disease: the more exposure to night-time light, the greater the risk. Even slight increases in night-time light were linked to increased brain and arterial pressure."
When the brain feels stressed, it activates signals that stimulate an immune response and cause inflammation of the blood vessels. Over time, this process can contribute to arterial sclerosis and increase the risk of heart attacks and strokes.
To counter the effects of artificial light at night, Abu Hashem suggested that cities reduce unnecessary outdoor lighting, cover street lamps, or use motion-sensitive lights.
He added: "People can reduce night-time indoor lighting, keep bedrooms dark, and avoid screens like TVs and personal electronic devices before sleep."
