Exposure to outdoor nighttime light pollution may increase the chance of Alzheimer’s disease more than other risk factors for people under the age of 65. This is according to research published in the journal Frontiers in Neuroscience.

The new study

The researchers, led by Rush University Medical Center associate professor Robin Voight-Zouvala, studied light pollution maps of 48 US states and divided the states into five groups, from lowest to highest nighttime light intensity.

They then incorporated into their analysis medical data on variables considered risk factors for Alzheimer’s disease.

Their results showed that for people aged 65 and older, the onset of Alzheimer’s was more strongly associated with nighttime light pollution than with some other disease factors, such as alcohol abuse, chronic kidney disease, depression and obesity.

In contrast, diabetes, high blood pressure and stroke were more strongly associated with Alzheimer’s than light pollution.

However, for the aged under 65 years of age the researchers found that higher nighttime light intensity was associated with higher incidence of Alzheimer’s disease than any other risk factor examined in the study.

This could suggest that younger people may be particularly sensitive to the effects of nighttime light exposure, the researchers say.

What about interior lighting?

While the researchers did not examine the effects of indoor light in the present study, they believe indoor exposure may be just as important as outdoor light exposure.

As they point out, the blue light has the biggest impact on sleep, so using blue light filters, switching to warm lighting and installing dimmers at home could effectively reduce light exposure.

The researchers note that the study was done in a subset of the US population, and that people may not live in areas with high light pollution throughout their lives, and these two parameters could affect the results.