Are nights truly dark? Not always. Indeed, some areas remain constantly illuminated, and this light could have unexpected consequences. Recent research reveals a surprising link between artificial nighttime light and Alzheimer's disease.
The study, conducted by an American team, focuses on light pollution and its potential effects on the brain. Published in
Frontiers in Neuroscience, it suggests that excessive exposure to outdoor light at night could be a significant risk factor for Alzheimer's disease.
For their investigation, the researchers analyzed light pollution maps of the United States. They compared this data with medical records of millions of people, dividing regions based on nighttime light intensity. The results are alarming.
Among people under 65, nighttime light appears more dangerous than other known risk factors, such as alcoholism or obesity. The researchers suggest that this population is particularly vulnerable due to urban lifestyles or specific genetic predispositions.
For those over 65, light pollution seems less influential than other factors like diabetes or stroke. However, it remains more significant than alcohol abuse or chronic illnesses.
The underlying biological mechanisms are not yet fully understood. It is possible that nighttime light disrupts the circadian rhythm or causes brain inflammation. An accumulation of beta-amyloid proteins, which are implicated in Alzheimer's disease, is also considered.
Experts recommend simple measures to limit these risks, such as using blackout curtains or eye masks. Adjusting indoor lighting by switching to warm lights or using filters is also suggested.
While this study highlights a troubling correlation, it remains incomplete. Researchers call for further work to explore these connections. Nighttime light has yet to reveal all its secrets.
What is light pollution and how does it affect our health?
Light pollution refers to the excess of artificial light produced by outdoor lighting at night, such as streetlights, illuminated signs, or building lighting. This phenomenon is especially pronounced in urban areas where nights are never completely dark.
It disrupts the circadian rhythm, the internal clock that regulates our sleep-wake cycle. Excessive exposure to nighttime light impedes the production of melatonin, the hormone that promotes sleep, which can lead to sleep disorders, affect mood, and potentially contribute to more serious conditions like Alzheimer's disease.
It also has harmful effects on the environment. Artificial light disorients nocturnal animals, disrupts ecosystems, and can even affect plants. Solutions include measures like using reduced lighting, warm-spectrum lights, and installing fixtures that direct light only where it is needed.
Article author: Cédric DEPOND