Researchers at the Cincinnati Children's Hospital Medical Center studied 249 children by asking their mothers about their children's sleep and behaviours.
They found that children who snored loudly at least twice a week at the ages of 2 and 3 had more behaviour problems than children who don't snore or snored at 2 or 3 but not at both ages.
The researchers found that lower socioeconomic status and a lack of breastfeeding or a short breastfeeding period as an infant were the strongest predictors of persistent snoring.
"A lot of kids snore every so often, and cartoons make snoring look cute or funny. But loud snoring that lasts for months is not normal, and anything that puts young kids at that much risk for behavioural problems is neither cute nor funny," lead researcher Dean Beebe said in a release. "That kind of snoring can be a sign of real breathing problems at night that are treatable. I encourage parents to talk to their child's doctor about loud snoring, especially if it happens a lot and persists over time."