Guilleminault tells WebMD that he first noticed a relationship between breathing problems and the baffling sleep disturbances in 1996, while conducting another study. "We did a very large survey on sleep disturbances and we noticed that frequent, recurrent sleepwalking and sleep terrors were much more common in those with abnormal breathing," he says. "But when we published the paper in Pediatrics, we didn't emphasize that finding enough. It was nagging at us, so we wanted to test it."
The new finding might not only bring answers to medical experts, but relief to parents. Sleep terrors can be particularly frightening, since these episodes often include screaming and crying, yet children are unresponsive to efforts to comfort them. Unlike nightmares, terrors are usually not remembered. Both sleep terrors and sleepwalking occur in the deepest stage or "slow-wave" sleep - usually within three hours after falling asleep; nightmares typically happen closer to waking.
"It certainly makes sense," says J. Catesby Ware, PhD, director of the Sleep Disorders Center at Eastern Virginia Medical School. "The thing that we do know about sleep terrors in children is that there must be something to produce a partial arousal from sleep. If someone placed a pillow on your face while you were sleeping, you would wake up because a cessation of breathing -- even partial -- produces an arousal."
These "arousals" prevent children from transitioning from slow-wave sleep to a lighter sleep stage. External factors like noise and light also cause arousals, along with physiologic conditions such as being "overtired" from lack of sleep and anxiety. "Normally, when we sleep, there's a very sharp distinction between awake and the different stages of sleep. With some of these disorders, the boundaries between those states are blurred," explains Hunt. "That is why with these conditions there are some behaviors that are typically awake-related occurring during sleep."
Guilleminault isn't suggesting that surgery be done to prevent these sleep disturbances in all children. "When they occur once in great while, or even in occasional bursts and then they disappear, that is perfectly normal and probably not because of breathing difficulties," he says. "The children in our study had persistent sleepwalking and terrors - occurring once or several times a week, every few weeks or so. And parents of children who have frequent episodes like that should probably have their breathing patterns evaluated."