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Exposure to bright artificial light could increase stroke risk

A recent study has revealed a disturbing link between excessive artificial light (aka light pollution) and an increased risk of stroke and other cerebrovascular diseases that affect the supply of blood to the brain.

Light pollution is the presence of excessive, poorly directed, or overly bright artificial light at night. Common sources of light pollution include streetlights, billboards, illuminated buildings, and other forms of outdoor lighting.

Sadly, this pollution harms human health, disrupts the delicate balance of ecosystems, and reduces our ability to enjoy the beauty of the natural night sky.

Impact of light pollution on the body

Sunlight plays a crucial role in our health, providing vitamin D and regulating our natural rhythms. However, artificial lights used for streets, homes, and workplaces affect our bodies in different ways. When you’re exposed to bright lights in the evening, it interferes with the production of a hormone called melatonin.

Melatonin is essential for your sleep cycle. It naturally increases in your body in the evening, signaling that it’s time to rest. Light pollution can disrupt melatonin production, making it harder to fall asleep and stay asleep. This leads to immediate problems like sleep deprivation, but could potentially have long-term health consequences.

Artificial light and stroke

The Ningbo study looked at data from over 28,000 adults living in the city, tracking their health for about six years. The researchers used satellite images to measure the amount of artificial light pollution each person was exposed to at night. They also took into account factors like air pollution, which is already a known risk for cardiovascular health.

The findings were concerning. The study revealed that individuals exposed to higher levels of artificial light at night had a significantly increased risk (43%) of developing cerebrovascular diseases such as stroke. These diseases affect the blood vessels and blood supply to the brain and are a major cause of disability and death.

Air and light pollution: Increased stroke risk

Additionally, researchers also discovered that high exposure to air pollution, particularly particulate matter (tiny particles like dust and diesel emissions), also increased the risk of cerebrovascular diseases. This aligns with existing research showing the detrimental effects of air pollution on cardiovascular health.

While the link between light pollution and cerebrovascular diseases was strong, the connection between light pollution and strokes specifically appeared weaker when analyzed alongside air pollution data. This highlights the complex nature of environmental factors and their impact on our health.

Further research is needed to fully understand how exposure to light and air pollution, both individually and combined, may influence our risk of stroke and other cerebrovascular diseases.

Artificial light as a stroke risk factor

“Our study suggests that higher levels of exposure to outdoor artificial light at night may be a risk factor for cerebrovascular disease,” said Dr. Jian-Bing Wang, one of the corresponding authors of the study. “Therefore, we advise people, especially those living in urban areas, to consider reducing that exposure to protect themselves from its potential harmful impact.”

While this study highlights a correlation (a link between two factors), it doesn’t definitively prove that light pollution directly causes an increased risk. However, the connection is strong enough to warrant caution and further research.

Protect your brain from stroke and artificial light

While you can’t single-handedly change the way cities light up, consider the following:

Blackout curtains

These thick curtains are designed to block out almost all external light, creating a dark, sleep-promoting environment in your bedroom. Investing in good-quality blackout curtains can significantly improve your sleep quality, especially if you live in an area with high light pollution.

Light therapy lamps

These lamps emit a specific type of light that mimics natural sunlight. This exposure can help regulate your circadian rhythm (your internal sleep-wake cycle). They are particularly useful for individuals who work night shifts or irregular hours, as well as those who live in areas with limited sunlight during certain seasons.

Warm night lights

If you need to have some light on at night, choose bulbs that emit warmer tones like red or amber. These wavelengths of light have a less disruptive effect on melatonin production compared to harsh white or blue lights.

Minimize screen time

Electronic devices like phones, laptops, and tablets emit blue light, which can significantly suppress melatonin and make it harder to fall asleep. Limiting your exposure to screens in the hours before bedtime can help improve your sleep quality.

Advocate for change

Become involved in initiatives within your community that aim to reduce light pollution. This might include supporting policies that promote the use of shielded, downward-facing outdoor lights, as well as energy-efficient lighting alternatives that minimize excessive brightness. By taking action, you can help create healthier environments for both humans and wildlife.

Impact of artificial lights beyond stroke

Beyond increasing the risk of conditions like stroke, light pollution poses a multitude of additional risks to both human health and the environment:

Sleep disorders

Artificial light at night significantly disrupts our natural circadian rhythms (our body’s internal clock), leading to sleep disorders like insomnia, difficulty falling asleep, and waking up frequently during the night. Chronic sleep deprivation has far-reaching health consequences.

Mental health issues

Disturbed sleep patterns and the disruption of circadian rhythms have been linked to mental health problems such as depression, anxiety, and even cognitive decline in the long term.

Obesity and metabolic syndrome

Research suggests that changes to our circadian rhythms triggered by light pollution can negatively impact metabolism. This has potential implications for weight gain, the development of type 2 diabetes, and other metabolic disorders.

Cancer risk

Studies point to a possible link between exposure to artificial light at night and an increased risk of certain types of cancer, particularly breast and prostate cancer. Scientists hypothesize that suppressed melatonin production caused by light pollution might play a role. However, more research is required to confirm this connection.

The bigger picture

This study adds to the growing body of evidence about light pollution’s harmful effects. We already know it messes with wildlife and disrupts natural ecosystems. It also wastes energy and contributes to climate change. Now, it seems, light pollution might be hazardous to our own health.

The American Heart Association stresses the importance of healthy sleep as part of its “Life’s Essential 8” for good cardiovascular health. With increasing research, perhaps managing light exposure will become another vital part of that list.

The study is published in the journal Stroke.


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