This common nighttime habit could increase your risk of stroke by more than 40%, new study warns

Spending time outside at night can be an integral part of a routine, providing the opportunity to move or at least breathe some fresh air. However, air pollution could make the air less fresh. Air pollution and exposure to artificial light – two common features of big city life – could increase the risk of stroke, new research suggests.

The research was published in March in Stroke, a journal of the American Heart Association (AHA). The findings suggest that continued exposure to bright, artificial light can increase the risk of developing a disease affecting blood flow to the brain by 43%. These conditions include blocked arteries, which can block blood supply and cause bleeding in the brain and lead to stroke.

The study also found that exposure to artificial light can decrease sleep — which might be your goal when you go out to relax at night — and also increase the risk of stroke.

“Environmental factors, such as outdoor lighting at night or artificial light, play an important role in our daily lives and well-being,” explains Dr. Mustali Dohadwala, MD, cardiologist and medical director of Heartsafe. “As our societies continue to rapidly modernize, environmental factors, particularly those that are artificially induced, are becoming increasingly prevalent and important.”

Indeed, researchers have found that 80% of the world’s population lives in a place polluted by light. If you’re one of them, this news probably isn’t welcome, but one doctor thinks it’s important.

“I think being forewarned is being forearmed,” says Dr. Trent Orfanos, MD, FACC, director of integrative and functional cardiology at Case Integrative Health. “When you know something poses a risk, you can do things to reduce that risk.”

Cardiologists shared their thoughts on the new research and how you can protect yourself.

Related: The #1 Mini-Stroke Symptom Most People Overlook, According to a Cleveland Clinic Neurologist

New study highlights environmental factors that increase stroke risk

The study included more than 28,3000 adults living in China. The researchers used satellite images showing light pollution to analyze data on participants’ exposure to artificial outdoor light at night. They followed the participants for six years between 2015 and 2021.

What did they find? Nearly 1,300 cases of cerebral blood vessel diseases. Of these cases, 777 strokes were triggered by blocked arteries (ischemic strokes) and 133 (hemorrhagic/hemorrhagic strokes) were attributed to bleeding in the brain. In total, people with the most exposure to outdoor light in the evening had a 43% higher risk of cerebrovascular disease than those with the lowest exposure levels.

Additionally, researchers noted that chronic nighttime exposure to bright light can suppress the body’s natural production of melatonin, a sleep-promoting hormone. The authors hypothesized that light exposure might impair sleep and, therefore, contribute to an increased risk of stroke.

“Lack of sleep can lead to high blood pressure, high blood sugar, weight gain, and abnormal heart rhythms,” explains Dr. Nieca Goldberg, MDauthor, medical director of Atria New York City and professor at NYU Grossman School of Medicine.

Bright lights weren’t the only factor that could increase the risk of stroke. People most exposed to air pollution from burning fuel, dust or smoke had up to a 50% higher risk of stroke. People exposed to the highest nitrogen oxide emissions via road traffic and industrial power plants had a 31% higher risk of stroke.

“Air pollution affects the heart by damaging blood vessels, which are therefore unable to provide an adequate blood supply, increasing the risk of blood clots, increasing blood pressure and disrupting the electrical activity of the heart,” explain Dr. Bradley Serwer, MDcardiologist and chief medical officer of VitalSolution.

If all of this information seems terrifying, we understand. But experts say the study has its flaws. “Importantly, this very well-thought-out longitudinal observational study generated some eye-opening results,” says Dr. Orfanos. “However, the study could not prove a causal link between artificial light at night and cerebrovascular events or air pollutants and cerebrovascular events because it was not a randomized intervention study by definition. its design.”

Additionally, participants came from only one city in China. “We would need to see if similar data is found in cities around the world,” says Dr. Goldberg.

Related: “I’m a cardiologist and this is the nut I eat almost every day for heart health”

What you can do to reduce your risk of stroke

1. Try to limit your exposure to light during the day if possible

In a perfect world: “It would be a good idea to get some sunlight during the day, which would properly set your body clock and melatonin production and help you sleep better at night,” says Dr. Orfanos. “Take a walk in the morning or at lunch, which will help you achieve this. Then in the evening, especially after sunset, turn off the lights indoors, which will help your body adjust to healthy sleep .”

2. Protect yourself outdoors

Various factors can hinder your ability to stay indoors when the artificial lights come on, such as working a third shift or simply having to walk from the subway to your apartment during the winter months when the sun goes down before the end of the work. You can still take steps to reduce your risk of stroke.

“Wear tinted glasses and wide-brimmed hats when you go out at night,” says Dr. Dohadwala. Dr. Dohadwala suggests wearing a face covering, preferably a medical-grade mask, to reduce exposure to air pollution at any time of the day.

3. Remember indoor precautions

What you do when you’re inside matters too. “Avoid watching TV or checking your phone or computer right before bed,” says Dr. Serwer. He also suggests using blackout shades to keep artificial light out.

4. Remember the basics

Exposure to artificial light and air pollution are not the only risk factors for stroke. “High blood pressure, atrial fibrillation, advanced age, high cholesterol, carotid and other artery diseases, smoking, physical inactivity, obesity and diabetes can also contribute to strokes” , explains Dr. Goldberg.

So no matter where you live, the basics of reducing stroke risk still apply. “Exercising, following a Mediterranean-style diet, and getting seven to eight hours of sleep are helpful in reducing strokes,” says Dr. Goldberg.

Next: 7 Simple Tips to Get Your Blood Pressure Under Control Quickly, According to Heart Health Experts

Sources

• Outdoor light at night, air pollution and risk of cerebrovascular disease: a cohort study in China. Stroke.

• Dr. Trent Orfanos, MD, FACC, Director of Integrative and Functional Cardiology at Case Integrative Health

• Dr. Mustali Dohadwala, MD, cardiologist and medical director of Heartsafe

• Dr. Nieca Goldberg, MD, medical director of Atria New York City and professor at NYU Grossman School of Medicine

• Dr. Bradley Serwer, MD, cardiologist and chief medical officer at VitalSolution.