There’s no denying that loud noise from traffic is annoying, but who knew it actually has the potential to cause you physical harm?

According to a new study from Denmark, the louder traffic is near a person’s home, the greater their risk of a heart attack.

Researchers studied 50,000 participants over the course of almost 10 years and found that the risk of heart attack went up 12 percent for every 10 decibels of additional traffic noise. This increased risk could be due to high levels of stress hormone, which people experience whenever they’re exposed to loud noises.

Above all, researchers warned, nighttime traffic is especially dangerous because it disturbs sleep. “You might wake up thinking that you had a quiet night, but when you look at it in a lab, you see that your sleep stages have been disturbed,” said Mette Sorenson of the Danish Cancer Society.

The link between traffic noise and heart attacks still held true even after researchers factored out high levels of pollution found near roadways. And they estimate that four percent of all heart attacks in Denmark are related to roadway noise.

So what’s the alternative? Sorenson suggests choosing an especially quite room to sleep in or soundproofing one’s home if necessary. Above all, she said, be aware, since most people don’t even realize when they’re being subjected to noise pollution.