Some hyperactive children thought to be suffering from attention deficit disorder may just be overtired because they are bad sleepers or heavy snorers, researchers said on Monday.

“To the parent, the message is if you have a kid who is hyperactive and snores, think about the possibility that the two may be connected,” study author David Gozal of the University of Louisville said.

In his study published in the journal Pediatrics, Gozal found roughly one-quarter of 5- to 7-year-old children with mild symptoms of attention deficit/hyperactivity disorder (ADHD) also snored. In some cases, the breathing problems reached the level of sleep apnea, where breathing is blocked repeatedly through the night and sleep is disturbed.