A large new study suggests that the sound of traffic outside your home at night could be doing more than disturbing your sleep—it may also be affecting your cholesterol and overall metabolic health.
Researchers from the University of Oulu in Finland found that people exposed to higher levels of nighttime road traffic noise had small but measurable changes in their blood lipids, including cholesterol and fatty molecules linked to heart disease and diabetes.
These changes are known risk factors for cardiometabolic diseases, which include conditions affecting the heart, blood vessels, and metabolism.
The study, part of the LongITools research project and published in the journal Environmental Research, analyzed health data from more than 272,000 adults aged 31 and older.
Participants came from three major European studies: the UK Biobank, the Rotterdam Study, and the Northern Finland Birth Cohort 1966. This makes it one of the largest investigations so far into how long-term traffic noise may influence the body.
To estimate noise exposure, researchers used national noise maps to calculate nighttime traffic noise levels at each participant’s home address. Nighttime noise was the focus because people are usually at home and trying to sleep, making them more vulnerable to disruption.
Blood samples from participants were examined using a sophisticated testing method that can measure many substances in the blood at once. The scientists looked at 155 different metabolic markers, including various types of cholesterol, fatty acids, and lipids that play important roles in the body.
They found that people exposed to nighttime traffic noise of about 50 decibels or more—roughly the sound level of a quiet conversation—began to show changes in these markers. At levels above 55 decibels, the changes were clearer.
Higher noise exposure was linked to increased levels of total cholesterol, LDL (“bad”) cholesterol, certain fat-rich lipoproteins, and other lipids involved in cell membranes and metabolism.
Although the changes for any individual were small, the researchers say the overall impact could be significant because so many people live near busy roads. The findings may help explain earlier studies that have linked traffic noise to heart disease and diabetes but did not fully understand the biological reasons why.
The scientists believe nighttime noise may disrupt sleep and trigger stress responses in the body, which can affect metabolism over time. They suggest that reducing traffic noise—through better urban planning, quieter road surfaces, or improved building design—could help protect long-term health.
The study adds to growing evidence that environmental noise is not just an annoyance but a public health issue. Creating quieter nighttime environments may be one simple way to support healthier hearts and bodies in the long run.
