September 9, 2024
Light Pollution Linked to Alzheimer’s in New Study
Exposure to outdoor light at night associated with higher prevalence of Alzheimer's Disease
Excessive outdoor light at night may increase the risk of Alzheimer's disease, especially in younger adults, according to a new study from researchers at Rush University Medical Center in Chicago. The research, published in the journal Frontiers in Neuroscience, adds to growing concerns about the health impacts of light pollution.
Researchers analyzed satellite data on nighttime light intensity across the lower 48 U.S. states and compared it to Medicare data on Alzheimer's prevalence from 2012-2018. They found a positive correlation between higher levels of nighttime light and increased rates of Alzheimer's disease.
Details of the Study
The study examined various sources of outdoor lighting, including streetlights, illuminated signs, and other forms of artificial outdoor illumination. Researchers used data from NASA's Visible Infrared Imaging Radiometer Suite (VIIRS) to measure nighttime radiance levels across different regions.
"We show that in the U.S. there is a positive association between Alzheimer's disease prevalence and exposure to light at night, particularly in those under the age of 65," said lead author Dr. Robin Voigt-Zuwala of Rush University Medical Center.
Age-related Findings
For adults over 65, the link between nighttime light and Alzheimer's was stronger than some known risk factors like alcohol abuse and obesity, though not as strong as factors like diabetes and hypertension. However, in adults under 65, nighttime light exposure had a stronger association with Alzheimer's prevalence than any other risk factor examined.
"Nightly light pollution – a modifiable environmental factor – may be an important risk factor for Alzheimer's disease," Voigt-Zuwala said.
Implications for Lighting Practices
The researchers noted that while 17 states have legislation designed to reduce light pollution, nighttime light levels were at their highest in 2022, the most recent year data was available. Dr. Voigt-Zuwala suggested that the findings could help inform lighting practices and policies. "This research underscores the need for more thoughtful outdoor lighting design that balances safety and aesthetic needs with potential health impacts," she said.
Simple steps like using fully shielded light fixtures, which direct light downward, and employing warmer color temperatures for outdoor lighting could help mitigate light pollution. On an individual level, using blackout curtains or sleeping masks may help reduce risk, especially for those in high light pollution areas.
Study Limitations and Future Research
The study had some limitations, including analyzing only Medicare data and not accounting for people's lifetime light exposure history or indoor light sources. The authors call for further research to better understand the relationship between nighttime light and Alzheimer's disease, including studies that measure individual light exposure more precisely.
As communities continue to grapple with balancing the benefits and drawbacks of nighttime lighting, this research adds another factor to consider in the ongoing discussions over how to light our world responsibly.
