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It might be tempting to think that noise isn’t a serious health issue, after all, it’s just noise. It won’t kill us … right? Well, maybe.

Exposure to prolonged or excessive noise has been shown to cause a range of health problems ranging from stress, poor concentration, productivity losses in the workplace, and communication difficulties and fatigue from lack of sleep, to more serious issues such as cardiovascular disease, cognitive impairment, tinnitus and hearing loss.

In 2011 the World Health Organization (WHO) released a report titled ‘’. This study collated data from various large-scale epidemiological studies of environmental noise in Western Europe, collected over a 10-year period.

The studies analysed environmental noise from planes, trains and vehicles, as well as other city sources, and then looked at links to health conditions such as cardiovascular disease, sleep disturbance, tinnitus, cognitive impairment in children, and annoyance. The WHO team used the information to calculate the disability-adjusted life-years or DALYs—basically the healthy years of life―lost to ‘unwanted’ human-induced dissonance. Their results might surprise you.

They found that at least one million healthy years of life are lost each year in Europe alone due to noise pollution (and this figure does not include noise from industrial workplaces). The authors concluded that ‘there is overwhelming evidence that exposure to environmental noise has adverse effects on the health of the population’ and ranked traffic noise second among environmental threats to public health (the first being air pollution). The authors also noted that while other forms of pollution are decreasing, noise pollution is increasing.

Interestingly, it may be the sounds we aren’t even aware we’re hearing that are affecting us the most, in particular, those we ‘hear’ when we’re asleep. The human ear is extremely sensitive, and it never rests. So even when you sleep your ears are working, picking up and transmitting sounds that are filtered and interpreted by different parts of the brain. It’s a permanently open auditory channel. So, although you may not be aware of it, background noises of traffic, aircraft or music coming from a neighbour are still being processed, and your body is reacting to them in different ways via the nerves that travel to all parts of the body and the hormones released by the brain.

The most obvious is interrupted sleep, with its flow-on effects of tiredness, impaired memory and creativity, impaired judgement and weakened psychomotor skills. Research has shown that people living near airports or busy roads have a higher incidence of headaches, take more sleeping pills and sedatives, are more prone to minor accidents, and are more likely to seek psychiatric treatment.

But there is another, more serious outcome. Even if you don’t wake up, it appears that continual noise sets off the body’s acute stress response, which raises blood pressure and heart rate, potentially mobilising a state of hyperarousal. It is this response that can lead to cardiovascular disease and other health issues.

A study undertaken by Dr Orfeu Buxton, a sleep expert at Harvard University, monitored the , who were played 10-second sound clips of different types of noise as they slept. The brainwaves of volunteers were found to spike in jagged, wake-like patterns of neural activity when each clip was played. This particular study was focusing on noises heard in a hospital environment—including talking, phones ringing, doors closing, machinery, toilets flushing, and city traffic, among others—but many of the sounds tested are ones we would also hear in an urban environment.

Sound is an important and valuable part of everyday life. But when sound becomes noise, it can negatively affect our mental and physical health. The realities of modern life mean the noises created in our world are not going to suddenly fall silent. Instead, we need to recognise that noise pollution is a serious health concern worthy of our attention, and find realistic and sustainable ways to manage and reduce it—starting with banning those rubbish truck pickups in the middle of the night!