How traffic could make you fat - research
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Living next to a busy road could increase the risk of obesity, the first research into the effects of noise pollution on waistlines has found.
Scientists say main roads often result in noise pollution from traffic, which can have an adverse reaction on residents' sleeping patterns and therefore their willingness to exercise.
Those who live near particularly busy roads may suffer from reduced energy levels following an interrupted night's sleep, and then show a lower inclination to exercise, instead choosing a more sedentary lifestyle.
The research, published in the British Medical Journal, found those who live under a flight path or near an airport were most likely to suffer from weight problems as a result of noise pollution.
Andrei Pyko, lead author of the study at Sweden's Karolinska Institutet, said traffic noise is a common and increasing environmental exposure because of urbanisation.
Road traffic is the dominating source, followed by railway and aircraft noise.
"Health effects related to traffic noise are widespread and span from annoyance, sleep disturbances and changes in stress hormone levels to adverse effects on the cardiovascular system."
Increasing evidence points to traffic noise as a risk factor for cardiovascular diseases such as hypertension, myocardial infarction and stroke.
Recent findings suggest that traffic noise may also affect the metabolic system, inducing central obesity and type 2 diabetes.
According to the study of 5075 men and women in Sweden, central obesity is associated with exposure to railway and aircraft noise and a particularly high risk was seen for combined exposure to all sources of traffic noise.
"Traffic noise may influence metabolic and cardiovascular functions through sleep disturbances and chronic stress," Dr Pyko said.
"Sleep is an important modulator of hormonal release, glucose regulation and cardiovascular function.
"Sleep disturbances may affect immune functions, influence the central control of appetite and energy expenditure as well as increase circulating levels of the stress hormone cortisol."
He said short sleep duration may lead to an increased appetite and reduced energy expenditure.