Nowadays, artificial lights ubiquitously illuminate our indoor and outdoor spaces. Artificial outdoor lights provide safety, convenience, and aesthetics, but excessive artificial light at night is called light pollution. Exposure to artificial outdoor light at night is associated with numerous detrimental health effects, including sleep disruption, obesity, depression, anxiety, memory dysfunction, atherosclerosis, and cancer, but little is known about the impact of light pollution on Alzheimer’s disease (AD).
A new study led by University of Cambridge scientists evaluated the relationship between outdoor nighttime light exposure and AD prevalence in the United States. The scientists used satellite-acquired outdoor nighttime light intensity and Medicare data.
This is the first time that light pollution has been associated with Alzheimer’s disease.
Lead investigator Robin Voigt-Zuwala, PhD, an associate professor at Rush, said, “Our research shows that there is an association in the U.S. between Alzheimer‘s disease prevalence and exposure to light at night, particularly in those under the age of 65.”
“Nightly light pollution — a modifiable environmental factor — may influence risk for Alzheimer’s.”
Scientists studied light pollution maps across the lower 48 states and examined medical data on Alzheimer’s disease. They split the data into five groups based on light intensity. They found that higher nighttime light levels were linked to more cases of Alzheimer’s disease, even when other known risk factors were considered.
While the cause isn’t clear, the study found that higher nighttime light levels were linked to more cases of Alzheimer’s in people under 65. This suggests that light exposure at night might affect younger people more than other risk factors.
Voigt-Zuwala explained, “Certain genes can influence early-onset Alzheimer’s, and these same genes may cause increased vulnerability to the effects of nighttime light exposure.”
“Additionally, younger people are more likely to live in urban areas and have lifestyles that may increase exposure to light at night.”
Artificial nighttime lighting, whether indoor or outdoor, disrupts circadian rhythms. Scientists did not examine light inside the home at night or how it might impact health.
Voigt-Zuwala said, “The good news is that simple changes can be made with minimal effort to reduce exposure to light at night—adding blackout curtains or sleeping with an eye mask.”
Journal Reference:
- Robin M. Voigt, Bichun Ouyang, Ali Keshavarzian. Outdoor nighttime light exposure (light pollution) is associated with Alzheimer’s disease. Frontiers in Neuroscience, 2024; 18 DOI: 10.3389/fnins.2024.1378498
