In some places in the world, the lights never go out. Street lights, road lighting and illuminated signs can deter crime, make roads safer and improve the landscape. However, excessive light pollution also has ecological, behavioral and health consequences.
In the United States, some states have legislation aimed at reducing light pollution; however, nighttime light levels remain high in many parts of the country. Now, researchers there have investigated correlations between and Alzheimer’s disease (AD).
“We show that in the US there is a positive association between AD prevalence and nighttime light exposure, particularly in those under 65 years of age. Nighttime light pollution, a modifiable environmental factor, may be an important risk factor for AD,” said Dr. Robin Voigt-Zuwala, associate professor at Rush University Medical Center.
The work was published in .
Excessive light pollution affects young people much more
The researchers studied light pollution maps in the lower 48 US states and incorporated medical data on variables known or thought to be risk factors for AD into the analysis. They generated nighttime light intensity data for each state and divided them into five groups, from lowest to highest nighttime light intensity.
The results showed that for people aged 65 years and older, the prevalence of AD was more strongly correlated with nighttime light pollution than with other risk factors such as , chronic kidney disease, depression and obesity. Other risk factors, such as diabetes, hypertension, and stroke, were more strongly associated with AD than light pollution.
For people under the age of 65, however, the researchers found that higher nighttime light intensity was associated with a higher prevalence of AD compared to any other risk factor examined in the study. This could suggest that younger people are particularly sensitive to excessive light pollution, the researchers said.
It is not clear why they might be more vulnerable, but it could be related to individual differences in light sensitivity. “Certain genotypes, which influence the early onset of AD, influence the response to biological stressors, which could explain the increased vulnerability to the effects of nocturnal light exposure. In addition, younger people are more likely to live in urban areas and have lifestyles that can increase light exposure at night,” explained Voigt-Zuwala.
How can we reduce light exposure at night?
The researchers hope their findings can help educate the public about the potential risks of nighttime lighting. “Awareness of the association should give people, especially those with risk factors for AD, the opportunity to make simple lifestyle changes. Easy-to-implement changes include using blackout curtains or sleeping with eye masks. This is especially useful for those who live in areas with high light pollution,” said Voigt-Zuwala.
Additionally, exposure to light inside the home could be just as important as exposure to light outside. Although the researchers did not examine the effects of indoor light in this study, they said that blue light has the greatest impact on sleep, and using blue light filters, switching to warm light and installing dimmer switches in the home could effectively reduce exposure to blue light. light.
The researchers pointed out that their results are based on a subset of the US population and that people may not live their entire lives in areas with high light pollution, both of which could influence individual results. The scientists also said that further research is needed to better understand how Alzheimer’s disease is influenced by nighttime light, .
