If you're a snorer, you've probably blamed it on allergies, too much alcohol, a lumpy pillow, or even your genes.
But new research suggests snoring is most likely caused by a combination of tiredness and exposure to traffic fumes.
An extensive study of 12,000 people found 25 per cent of men snored heavily at least three nights per week, with those exposed to traffic pollution the most likely to do it.
The snoring study was conducted at Bergen University in Norway, where researchers believe toxic gases and particles released by engines, particularly diesel, could be the cause.
Researchers said air pollution can cause snoring due to an increased level of inflammation in the body. Traffic noise is also believed to disrupt sleeping patterns, leaving us tired and restless.
Ane Johannessen, an epidemiologist at Bergen University in Norway, told the Daily Mail: "We know that people exposed to secondary cigarette smoking are more likely to snore, so we wondered if the toxins from traffic pollution might also be linked to snoring."
Scientists also discovered a difference between the way men and women were affected by traffic pollution and snoring.
Men who slept in bedrooms near to traffic-heavy roads were susceptible to increased snoring due to air pollution and traffic noise.
While women with similar sleeping arrangements were more susceptible to daytime sleepiness.
The data was collected from cities throughout Europe, and highlights the extent to which traffic pollution disrupts our health.