A Canadian study finds that about a third of toddlers who experienced sleep terrors became sleepwalkers later in their childhood, reports WXXI News.

“It was thought for a long time that these were related to stress and psychological unrest,” said Dr. Heidi Connolly, chief of Pediatric Sleep Medicine at Golisano Children’s Hospital. “Really, what the issue is, is that these things cause sleep deprivation. And then, if you’re more sleep- deprived, you’re more likely to engage in sleep walking or night terrors.”