WHAT THEY’RE SAYING
Research suggests that there is a link between exposure to traffic noise and body weight, particularly abdominal obesity.
WHAT THIS MEANS
There is evidence that traffic noise, whether from cars, planes or trains, affects us on a deeper level than we might have originally assumed. Traffic noise is undoubtedly stress-inducing and irritating, but what impact does this type of noise have on the human body long-term? Researchers are now exploring the connections between traffic noise and the body’s physical response.
Traffic noise affects the body in two primary ways: through sleep disturbances and chronic stress. If you’ve ever lived in an urban area or along a busy road or close to a train station or airport, you understand what this means. It means loud noises frequently and unpredictably punctuating the peace and quiet of your home or office. It means sirens wailing, helicopters flying overhead, planes descending into the airport and cranky morning commuters leaning on their horns as they scream angrily at the car ahead that just cut them off.
Traffic noise impacts the metabolic system through elevating levels of the stress hormone called cortisol. Higher levels of cortisol induce the body’s stress response, known as the “fight or flight” response. This response activates the sympathetic nervous system and the endocrine system. Prolonged elevated cortisol levels can be the result of sleep disturbances. When your body is sleep-deprived, hormonal regulation is effected, thus influencing your body’s regulation of cortisol.
WHY THIS MATTERS
Cortisol plays a role in the body’s accumulation of abdominal fat.1 Researchers in Sweden hypothesized that Swedish residents exposed multiple sources of traffic noise (cars, trains and planes) would have higher levels of obesity than residents who were not exposed to these types of noises.
In total, 5000 men and women participated in the study. Participants answered questions on lifestyle habits, food behavior, smoking, alcohol intake and physical activity, as well as health status, psychological distress, insomnia and job strain. They were also asked questions on noise annoyance and noise sensitivity. Trained nurses measured the height and weight of participants, as well as their waist and hip circumference.
In total, 46% of participants were exposed to road traffic noise, 8% only to aircraft noise and 0.3% to railway noise. Overall, 54% were exposed to one of the three sources, 15% to two of the sources and 2% to all three sources. There was an exposure-response association between the number of traffic noise sources and a person’s risk of abdominal obesity. The risk of abdominal obesity in those exposed to one source of traffic noise was 25% greater than participants who were not exposed, and in participants exposed to all three forms of traffic noise, risk was nearly double.
The relationship between lifestyle and obesity is remarkably complex. Where a person lives shapes her/his food environment, which may or may not lend itself to nutritious and affordable food choices. It influences the ability to be physically active, whether through the presence of sidewalks for walking or running or due to a level of violence that may make it unsafe to be outside. Place of residence influences the jobs offered, which could pose a potential threat to sustainable employment. Controlling for these other factors, this research suggests that people living in noisy, high-volume traffic areas are more likely to have increased abdominal fat than those who do not live in this type of area. Given the connection between stress and obesity, we suggest developing ways to reduce stress in your life as a means to an overall healthy lifestyle.
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