Night Time Light Pollution Linked to Alzheimer’s Disease

While the link between Alzheimer’s disease and some facets of modern life (like diet and lack of exercise) is not surprising, a new study has found another unexpected risk factor: night-time light pollution. This study compared Alzheimer’s disease prevalence with satellite data to determine nighttime light intensity from 2012-2018 in the lower 48 US states. Florida, Connecticut and New Jersey had high levels of both nighttime light pollution and Alzheimer’s disease while Montana, New Mexico, Vermont, Idaho, Wyoming and Oregon had lower levels of both. The association between nighttime light pollution and the risk of Alzheimer’s is highest among those below the age of 65.

Shockingly, this study found that night-time light pollution was more strongly associated with Alzheimer’s disease than alcohol abuse, chronic kidney disease, depression, heart failure, and obesity. Yes, you read that right. Atrial fibrillation, stroke, diabetes, and hyperlipidemia were more strongly linked to Alzheimer’s disease.

In animal studies, exposure to light during times when the brain has evolved to expect darkness increases the risk of neurodegenerative changes. How night light pollution increases this risk remains a mystery but a potential hypothesis is that nighttime light exposure may disrupt sleep quality. Disturbed sleep not only induces neuroinflammatory changes but also can impair glymphatic clearance of waste products and toxins from the brain.

We can’t really avoid some sources of nighttime light pollution like street or outdoor building lights. A simple way for us to reduce our exposure to light at night is to limit exposure to electronic screens (e.g., phones, tablets, TVs, computers, laptops) and keep our bedrooms as dark as possible.