Context: Researchers in the US have found a correlation between light pollution at night and the incidence of Alzheimer’s disease. Exposure to artificial light at night is one environmental factor that could be a significant risk factor in causing Alzheimer’s disease.
Light pollution
- Light pollution is the excessive artificial light in the night which disrupts the natural darkness of the night sky.
- This light can come from various sources, including streetlights, billboards, commercial buildings, and residential homes.
Impacts of light pollution:
As much as 80% of the global population experiences light pollution. Although these artificial night-time lights are most often seen as harmless, they have numerous negative impacts both to humans and the environment.
- Human health: Exposure to light at night can disrupt a person’s circadian rhythm (body’s natural sleep-wake pattern), which can lead to hormonal imbalances and other health issues, like sleep disorders, eye problems, and potentially increased risk of certain diseases like Alzheimer's.
- Impact on plants: During the day, plants need sunlight for photosynthesis. However, during the night, they require darkness to replenish a crucial molecule called phytochrome, which controls several important plant processes like photoperiodism, abscission, dormancy, and seed germination. According to recent research, light pollution near lakes inhibits zooplankton from consuming surface algae, leading to algal blooms that can kill the lake's vegetation and degrade the water's quality.
- Impact on animals: Artificial light can interfere with nocturnal species' natural behaviours like ability to navigate in darkness (may become blinded), breeding patterns and disturb prey-predator dynamics.
- Impact on birds: The seasonal migration schedule of migrating birds is guided by the light from the moon and stars. But due to light pollution, they may migrate too early or too late as a result, thus they can miss the best weather conditions for nesting, feeding, and breeding, and may get diverted from their intended migratory path.
- Impact on sealife: During their mating period, the females sea turtles approach the beach to deposit their eggs. Hatchlings instinctively move towards the brighter horizon (identify the sea by spotting the bright horizon across the water), but the artificial beachfront lighting confuses them, leading them inland which can be fatal.
- Astronomy: Light pollution creates a bright glow in the night sky, making it difficult to observe faint astronomical objects like stars, galaxies, and nebulae and interferes with astronomical observations.
Alzheimer disease:
- Alzheimer is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. It is the most common type of dementia — a continuous decline in thinking, behavioural and social skills that affect a person’s ability to function independently.
- Causes: The disease is thought to be caused by the abnormal build-up of proteins in the brain, and the accelerated ageing of certain neurons concerned with storage and processing of memory.
- One of the proteins involved is called amyloid, deposits of which form plaques around brain cells.
- The other protein is called tau, deposits of which form tangles within brain cells.
- Symptoms: Early signs include forgetting recent events/conversations. Later, the person will develop severe memory impairment and lose the ability to carry out everyday tasks. In the advanced stages, complications from severe loss of brain function result in death.
- Treatment: Currently, there is no cure for Alzheimer’s disease, but certain medications can temporarily slow the worsening of dementia symptoms.
- According to WHO estimates from 2023, more than 55 million people suffer from dementia worldwide, with Alzheimer’s contributing to around 75% of these cases.
