New research suggests that exposure to nighttime light could be linked to a higher prevalence of Alzheimer’s disease, particularly among younger individuals. Researchers analyzed satellite data on nighttime light intensity across U.S. states and counties from 2012 to 2018, alongside Medicare reports of Alzheimer’s disease prevalence. While conditions like diabetes and hypertension were more strongly correlated with the disease, nighttime light exposure was found to have a stronger link to Alzheimer’s than factors such as alcohol abuse, chronic kidney disease, depression, heart failure, and obesity.
The study’s findings were especially significant for people under the age of 65, where nighttime light exposure was more strongly associated with Alzheimer’s prevalence than any other health factor examined. This suggests that younger people may be particularly sensitive to the effects of nighttime light, possibly due to the disruption of circadian rhythms—our biological clock that governs sleep and wake cycles.
Dr. Robin Voigt-Zuwala, an associate professor at Rush University Medical Center and co-author of the study, emphasized that nighttime light exposure disrupts circadian rhythms, potentially making individuals more susceptible to Alzheimer’s disease. She also noted that younger individuals, who are more likely to live in urban areas with higher light pollution, may face increased exposure.
The researchers acknowledged some limitations of the study, including that Medicare data only reflects current residences, not lifelong exposure to nighttime light. Additionally, the study measured Alzheimer’s prevalence rather than incidence, meaning it focused on the proportion of people currently living with the disease rather than new cases.
Despite these limitations, experts say the findings highlight the importance of maintaining healthy sleep patterns. Dr. Samuel Gandy, an Alzheimer’s researcher at Mount Sinai in New York, noted that poor sleep is a known risk factor for Alzheimer’s, and nighttime light exposure can lead to shorter sleep durations and poorer sleep quality.
The study’s authors hope the findings will encourage people to make small lifestyle changes, such as using blackout curtains or sleeping with eye masks, to reduce nighttime light exposure and protect their brain health. More research is needed to fully understand the relationship between light pollution and Alzheimer’s disease.