Nov 03, 2015 12:31 AM EST By J Dionne, UniversityHerald Reporter

New research suggests that sleepwalkers are unlikely to feel pain during an episode, even while suffering an injury.

Researchers found that sleepwalkers were nearly four times more likely than controls to report a history of headaches (odds ratio = 3.80) and 10 times more likely to report experiencing migraines (OR = 10.04), after adjusting for potential confounders such as insomnia and depression. Among sleepwalkers with at least one previous sleepwalking episode that involved an injury, 79 percent perceived no pain during the episode, allowing them to remain asleep despite hurting themselves.

"Our most surprising result was the lack of pain perception during the sleepwalking episodes," Dr. Regis Lopez, principal investigator of the study and psychiatrist and sleep medicine specialist at Hospital Gui-de-Chauliac, said in a statement. "We report here, for the first time, an analgesia phenomenon associated with sleepwalking."

For the study, researchers conducted the cross-sectional study of 100 healthy control subjects and 100 patients with a diagnosis of sleepwalking, including 55 males and 45 females. Sleepwalkers had a median age of 30 years. Daytime pain complaints were evaluated by a clinician and self-report questionnaires, which assessed lifetime headache frequency and headache characteristics.

IN the study, 47 sleepwalkers reported having experienced at least one injurious sleepwalking episode. Only 10 reported waking immediately due to pain; the other 37 perceived no pain during the episode, but felt pain later in the night or in the morning.

"Our results may help to understand the mechanisms of the sleepwalking episodes," Lopez said. "We hypothesize that a dissociate state of arousal may modify the components of sleep-wake behavior, consciousness, and also pain perception."

The findings are detailed in the journal Sleep.

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