Sleep quality is considered one of the key factors affecting cardiovascular health. Studies have shown that nighttime noise associated with urban traffic can impact sleep even in young and healthy individuals.

The Impact of Noise Pollution

In recent years, environmental noise pollution has been recognized not only as a source of discomfort but also as a public health risk factor. According to the European Environment Agency, approximately 150 million residents of the European Union are exposed to harmful levels of road traffic noise, which is the main source of urban noise.

Epidemiological studies have identified a link between long-term residence in noisy areas and an increased risk of cardiovascular diseases, including hypertension, coronary heart disease, and heart attacks. However, the biological mechanisms behind this effect remained unclear for a long time.

Experimental Study

A team of researchers from the University Medical Center Mainz (Germany) conducted an analysis of the effects of nighttime road noise on the health of young people under controlled conditions. The study involved 74 volunteers around 26 years old, all without chronic illnesses and not taking any medications. Each participant spent three nights in their own bedroom under different acoustic conditions. The order of the nights was randomized, and neither the participants nor the staff knew which night was coming up.

• On the first night, there was no additional noise (control night).
• On the other two nights, recorded sounds of passing cars were played: one night featured 30 noise events, and the other 60. The peak volume of each event was about 60 decibels, comparable to normal conversation and similar to the noise level entering a bedroom with an open window in a busy area.

Health Assessment

Each morning after the study nights, the condition of the endothelium—the inner lining of blood vessels—was assessed, and a clinical blood test was performed. Throughout the night, continuous recordings of electrocardiograms and noise levels were made to monitor heart reactions to noise peaks. Participants also completed questionnaires about their sleep quality.

Main Results

The results showed that even relatively quiet but intermittent nighttime noise can have an immediate negative effect on the body of a healthy person. There was a significant deterioration in vascular function: the endothelium assessment indicator dropped from 9.35% on the control night to 7.73% after the night with 60 noise events. This indicates a reduced ability of blood vessels to dilate, which is considered an early predictor of cardiovascular disease.

Noise also triggered activation of the autonomic nervous system. Analysis of nighttime recordings revealed that after each noise peak, a spike in heart rate was highly likely to follow. The maximum pulse during the noisiest night was on average eight beats per minute higher than during the quiet night, indicating stress and disruption of the body's full nighttime recovery.

Participants themselves rated their sleep quality after noisy nights as significantly worse, which was also confirmed by blood test results. The most pronounced molecular changes were observed in those volunteers whose blood vessels were most affected by the noise.

Study Limitations

The study sample included only young and healthy individuals, which does not allow the findings to be directly applied to older people or patients with existing conditions who may be more vulnerable. Additionally, the study examined only the acute effects of noise over a single night and does not provide a complete picture of the cumulative impact of chronic noise exposure or possible adaptation mechanisms.