Kazantseva Olga/ShutterstockHas your phone ever died very quickly, despite you barely using it? Sometimes, the explanation is simple: dozens of apps running in the background constantly drain the battery. Something similar happens within our bodies, as almost all of us live with an app installed by default that never closes: noise.This invisible aggressor is not just a physical phenomenon that can be measured in decibels – it is a subjective, cultural experience. As philosopher Byung-Chul Han points out, our society has pushed silence to the margins, replacing it with a constant state of hyper-attention that keeps the body in a state of low-level alertness. What begins as a sensory stimulus ends up fuelling a crisis of attention and biological rest. Human beings evolved to interpret sounds as signals of danger or relevant information. For millennia, hearing the crack of a branch was all that stood between survival and dying at the hands of a predator, but over just a few decades our soundscape has changed radically. Traffic, construction, constant notifications and urban hum have created a perpetual soundscape, and our bodies have simply not had enough evolutionary time to adapt to this barrage. Leer más: A new study has linked traffic noise and pollution to infertility - but the effects differed for men and women For years, research focused on hearing health, and with good reason – noise is the second leading cause of hearing loss worldwide. In recent decades, “recreational” noise exposure has come to the fore, particularly prolonged headphone use among young people.But the most significant change in modern science is not just about the amount of noise, but how we experience it. Noise is no longer understood solely as a problem that affects hearing, it is also recognised as a systemic environmental pollutant. Transport noise is now one of the leading environmental cause of illness in Europe, second only to air pollution.The human body does not process all sounds in the same way. Below a physiological threshold of around 60 decibels (a normal conversation), the body keeps its balance. But above this limit, the nervous system interprets the sound stimulus as a threat and triggers the instinctive fight-or-flight response. The sound itself does not matter. Whether it is a motorbike or a distant siren, the brain perceives it as a potential danger, meaning any sound over the threshold activates the hypothalamic-pituitary-adrenal axis. This triggers a sustained release of cortisol and adrenaline, the stress hormones that put us into survival mode. Leer más: Superblocks: Barcelona’s car-free zones could extend lives and boost mental health Impacts on the heart and gutWhen this survival mechanism is chronically activated, health suffers. Continued noise exposure raises the heart rate and blood pressure, increasing the risk of high blood pressure, heart attack and stroke.The effects also extend into unexpected areas, including the gut microbiota. Recent research suggests that the vast ecosystem of bacteria living inside us is particularly sensitive to our environment and behaviour, and chronic stress caused by noise could disrupt the balance of this ecosystem. This causes what scientists call “dysbiosis”: a kind of bacterial mutiny, where beneficial bacteria populations decline and harmful ones take over.Even while we sleep, the brain does not switch off. It continues to process sounds and keep the body in a state of micro-alertness that disrupts our rest. This lack of night-time recovery is the ideal breeding ground for oxidative stress and systemic inflammation, which are linked to metabolic diseases such as type 2 diabetes.The luxury of silenceOur senses are closely linked to our health, but access to peace and quiet is not distributed equally. In Spain, for instance, 83.9% of people live in urban areas, and noise exposure is determined by postcode – the most densely populated areas are subject to a constant barrage of noise, making them epicentres of vulnerability. Noise is therefore a matter of social inequality. Less well-off people not only breathe poorer air, but also live in noisier environments that prevent their bodies from healing and resting.The solution is not just external. A body already under stress from emotional factors or poor diet is more vulnerable to noise pollution, meaning nutrition can make a difference. Diet cannot, of course, silence noise, but antioxidants and essential nutrients can boost our stress tolerance, protecting sensitive tissues and strengthening the resilience of the gut ecosystem. Leer más: Car-free streets reduce noise and air pollution. More cities should have them Turning down the volumeThe fight against noise pollution requires public policies: reducing traffic, improving sound insulation in homes, and building green spaces that act as refuges. A cultural shift is also needed. Revaluing silence means recognising it as a vital biological resource.On an individual level, we can take small steps to improve our “sound diet”. These include silencing unnecessary notifications, or carving out moments of complete disconnection during the day. In a society that prioritises speed and excess, silence becomes a subversive act. It is not about eliminating sound altogether, but about restoring balance. The most important question is not how much noise we can tolerate, but how much silence we need to be truly healthy.In a world that pushes us to be constantly connected, rediscovering silence is the best possible way to recharge. We must learn to consciously close the app draining our energy in the background, and remember that silence is not a system error – it is the only state in which our operating systems can truly rest and reboot. In cities where silence can only be enjoyed by a privileged few, peace and quiet ceases to be a personal choice. Instead, it becomes a public health right, one that must be protected and prioritised on all levels. A weekly e-mail in English featuring expertise from scholars and researchers. It provides an introduction to the diversity of research coming out of the continent and considers some of the key issues facing European countries. 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