Street lamps, illuminated signs… big cities never sleep. While night lighting has certain advantages, particularly in terms of security, the ecological and health consequences are significant. Recently, researchers have even discovered that outdoor nighttime light pollution could increase the risk of Alzheimer’s disease. Fortunately, this is a modifiable environmental risk factor.
To reach this conclusion, the researchers studied the light pollution maps of the 48 contiguous United States, as well as variables known to be risk factors for Alzheimer’s. They found that among those aged 65 and over, the prevalence of dementia was more strongly correlated with nighttime light pollution than with other risk factors such as excessive alcohol consumption, chronic kidney disease, depression and obesity. Other factors such as diabetes, high blood pressure and stroke were more strongly associated with Alzheimer’s than light pollution.
In contrast, among those under 65, high nighttime light intensity was associated with a higher prevalence of Alzheimer’s disease than any other risk factor. Thus, young people would be particularly sensitive to the effects of exposure to nighttime light.
Install blackout curtains and sleep with a mask
It is unclear why young people are most vulnerable. It could be due to individual differences in sensitivity to light, the researchers suggest.. “Certain genotypes, which influence the early onset of Alzheimer’s disease, have an impact on the response to biological stressors, which could explain an increased vulnerability to the effects of exposure to night light, explains Dr. Robin Voigt-Zuwala, first author of the study and associate professor at Rush University Medical Center. Additionally, young people are more likely to live in urban areas and have lifestyles that may increase their exposure to light at night.”
While further research on the subject is needed, the scientists hope their discovery will help raise awareness of the potential risks of nighttime light. “Awareness of this link should empower people, particularly those with risk factors for Alzheimer’s disease, to make simple lifestyle changessays Dr. Voigt-Zuwala. Easy changes to implement include using blackout curtains or wearing an eye mask to sleep. This is especially helpful for those who live in areas with high light pollution.
In this study, the researchers focused on outdoor light, but it is proven that blue light has impacts on health and especially on sleep, they point out. Also, they encourage people to favor warm lights and install dimmers at home. Further research is needed to understand how nighttime light influences Alzheimer’s, they conclude.
Mosquitoes, insomnia and AMD
The health disadvantages of blue light, carried by screens and LED bulbs, are regularly proven by science. In particular, we know that it is toxic to the retina. In 2019, ANSES confirmed “short-term phototoxic effects linked to acute exposure and long-term effects linked to chronic exposure, which increase the risk of developing age-related macular degeneration (AMD)”. In addition, exposure to blue light in the evening disrupts biological rhythms and therefore sleep, recalled the Academy of Medicine in a report published in 2023. “This is because during chronic exposure to light during the night, including screens (smartphones, tablets, computers), sleep-wake rhythm disorders appear in connection with a desynchronization of the internal clock,” it explained, recommending the use of anti-blue light glasses, at all ages but especially in children and adolescents in whom the lens is more translucent and therefore more fragile.
As for outdoor light pollution, in addition to its possible links to Alzheimer’s disease, it has also been shown to be linked to increased mosquito activity. In fact, the high brightness of cities sends the wrong signal to mosquitoes. Instead of hibernating when temperatures start to drop and days get shorter, females continue to reproduce and bite.
Source: www.topsante.com
