A new study published in Cardiovascular Research shows that even a single night of road traffic noise, at levels typical for people living in cities, can place measurable stress on the heart and blood vessels. The findings may help explain why long-term exposure to traffic noise has been linked to higher rates of high blood pressure and cardiovascular disease.
In the study, 74 healthy adults were exposed to different levels of nighttime road traffic noise. The results showed that even low-level noise impaired blood vessel function, increased heart rate, and disrupted sleep. Researchers also detected changes in blood proteins associated with inflammation and physiological stress in participants exposed to nighttime noise.
Findings showed that even a single night of road traffic noise stressed the cardiovascular system. Study researchers did not expect to see such consistent biological changes in people exposed to noise levels typical of living near a road.
The findings support calls from the European Society of Cardiology and the World Health Organization for stricter noise regulations. They also highlight the importance of urban planning strategies that protect sleep and cardiovascular health in increasingly noisy environments.
Participants took part in the study for three nights and were exposed to one of three conditions each night: no noise (control), 30 traffic noise events, or 60 traffic noise events. The study was double-blinded, meaning that neither the participants nor the researchers measuring their health outcomes knew which noise condition was used on a given night.
The following morning, participants underwent several health assessments, including flow-mediated dilation, a standard test of blood vessel function. Lower dilation percentages indicate impaired vascular function and are associated with increased cardiovascular risk.
The average flow-mediated dilation in the control condition was 9.35%. This decreased to 8.19% after exposure to 30 nighttime traffic noise events and to 7.73% after exposure to 60 noise events, indicating progressively poorer vascular function with increasing noise exposure.
Blood sample analysis also revealed changes in interleukin signalling and chemotaxis among participants who showed the most pronounced vascular impairment. These biological pathways are closely involved in inflammation and stress responses.
These are the same key biological pathways that have been altered by noise exposure in multiple mouse studies. This allows researchers to link molecular mechanisms identified in preclinical models with the cardiovascular effects now observed in humans.
Noise exposure also increased participants’ average heart rate by 1.23 beats per minute. In addition, self-reported sleep quality and feelings of restfulness declined significantly after nights with traffic noise.
Even when humans are asleep, their bodies are still listening. Repeated activation of stress responses night after night may help explain why people exposed to long-term traffic noise have higher rates of high blood pressure and heart disease. Addressing noise pollution should therefore be considered part of cardiovascular disease prevention in cities worldwide.
During the study, participants were required to avoid alcohol, caffeine, nicotine, recreational substances, and strenuous physical activity. Traffic noise recordings were played in their bedrooms overnight, and compliance was monitored through continuous sound-level recording. Each traffic noise event peaked at approximately 60 decibels and consisted of real-world traffic recordings.
Researchers note that Individuals may be able to reduce their exposure by moving bedrooms away from busy roads or installing high-quality sound-insulated windows. Earplugs may also help reduce perceived noise, although there is currently limited evidence that they protect against cardiovascular effects. Maintaining healthy lifestyle habits, including balanced diets and regular exercise, may also mitigate risk.
However, the researchers emphasised that the most meaningful improvements would likely come from broader structural measures, such as reducing nighttime traffic, implementing quieter road surfaces, improving urban planning, and enhancing building insulation.
Transportation noise should be formally recognised as an independent cardiovascular risk factor in future clinical prevention guidelines. Consistent epidemiological and mechanistic evidence links chronic noise exposure with hypertension, ischaemic heart disease, stroke, and cardiometabolic dysfunction, even at levels below current regulatory thresholds.
According to estimates from the European Environment Agency, around 150 million people, more than 30% of the population in the European Economic Area, are exposed to unhealthy levels of transportation noise above the World Health Organization’s recommended limits. Road traffic is the primary source of this exposure, accounting for the majority of affected individuals.
The researchers note that the study assessed short-term effects in young, healthy adults. Further research will be needed to determine how these findings translate into long-term cardiovascular risk. Future studies are also planned to confirm the observed blood protein changes in larger populations.
Source: ESC
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