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By Stephen Beech
People living near noisy roads or airports are more likely to suffer a heart attack or stroke — even if they get healthy sleep, warns new research.
The findings show that transportation noise is linked to a higher risk of heart-related health issues — including high cholesterol and high blood pressure — regardless of how much shut-eye people get.
Researchers found that people exposed to high levels of residential transportation noise — including road traffic, trains and aviation — face a higher risk of serious heart conditions.
The link was similar for people who get seven to nine hours of sleep every night and those with unhealthy sleep patterns or suffering from a sleep disorder.
American scientists say their findings suggest that chronic exposure to loud transportation noise may be an environmental risk factor that increases the risk of cardiovascular disease, which healthy sleep patterns may not counteract.
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Lead author Dr. Joseph Nguyen said: “The key finding of our study is that the relationship between noise exposure and cardiovascular disease events, and the number of cardiovascular risk factors developed, was similar among people with and without unhealthy sleep, suggesting that healthy sleep is not protective against adverse heart impacts of noise exposure.
“We expected that disordered sleep would influence the relationship between noise exposure and heart disease.
“It was surprising to find that sleep health appeared to play no role.”
Road traffic noise has become a major issue, but research indicates that noise from other forms of transportation — such as jet aircraft — can also increase the risk of heart disease.
The World Health Organization states that noise is a public health risk and has set limits on noise exposure to try to reduce the effects.
Researchers analyzed medical records and lifestyle survey data for more than 108,000 adults, as well as U.S. government transportation noise data, to examine whether transportation noise-related heart risks differed between people with normal and abnormal sleep.
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Specifically, they examined average noise levels above 45 to 50 decibels, which is similar to moderate rainfall or typing on a keyboard.
Dr. Nguyen, an internal medicine resident physician at Massachusetts General Hospital, Boston, said: “It is important to note that the noise levels in our dataset are a 24-hour average, rather than peak noise levels, which may be much higher.
“For example, subway stations have an average noise level of about 75 decibels at rest and can be more than 100 decibels when trains are arriving or leaving.”
Around a third of the participants (33%) were exposed to transportation noise louder than 50 decibels, and 54.5% were exposed to noise louder than 45 decibels.
The findings showed that exposure to elevated levels of transportation noise — above 50 decibels — was associated with an 8% to 10% increase in the development of major heart disease risk factors, such as high cholesterol, high blood pressure and diabetes.
Transportation noise exposure at more than 50 decibels was linked to greater odds of developing a major adverse heart event, even after accounting for age, sex and sleep quality.
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Dr. Nguyen said: “While our primary analysis focused on the number of risk factors developed, as opposed to which specific risk factor was most affected, when analyzing risk factors individually, the strongest relationship was seen with high cholesterol, followed by high blood pressure and then diabetes.”
He said the link between transportation noise and cardiovascular events was similar for those with healthy and unhealthy sleep — even after considering other factors that affect heart disease risk, including high blood pressure, high cholesterol, diabetes and air pollution.
Dr. Nguyen says the findings, due to be presented at the American Heart Association’sScientific Sessions meeting in Chicago later this week, highlight the importance of limiting environmental noise exposure.
He added: “People with noise exposure should consider strategies to reduce noise levels, such as installing thicker drywall, windows and doors in their home; placing bedrooms in the quietest areas of the house; planting dense trees and vegetation in the yard to absorb noise; and using earplugs during sleep.”
Dr. Keith Churchwell, of the American Heart Association, welcomed the findings.
He said: “This study adds to the growing evidence that shows environmental factors such as air pollution, noise, artificial light, chemical pollutants and climate-related events may be contributing to the significant burden of cardiovascular disease as a leading cause of death worldwide.”
Dr. Churchwell added: “Creating stronger policies to reduce adverse environmental exposures and building durable infrastructure that emphasizes wellness, will help us tackle these environmental issues and help improve heart health, and create healthier, more sustainable communities for our children and our children’s children.”
