For sleepwalkers, nighttime can be dangerous. Whether walking for miles in socks or crashing through a glass window, people have reported waking up with all manner of injuries after sleepwalking. Though it seems odd that these painful feats don't wake their unsuspecting performer, a new study found that some sleepwalkers feel no pain during sleep.
A group of researchers from Hospital Gui-de-Chauliac in Montpellier, France surveyed 100 patients who reported sleepwalking at least once in the previous year. 80 percent of people who injured themselves while sleepwalking said they didn’t feel any pain until after they woke up, Beth Mole reports for Ars Technica.
Even worse, people who sleepwalk may not only be impervious to pain if they get injured while sleeping, but they may also be more susceptible to things like chronic pain and migraines while awake, according to the study recently published in the journal Sleep
When someone starts sleepwalking, they’re not actually asleep: It’s more like their brain started to wake up, but got stuck somewhere along the way. Sleepwalking is most common among children, but it’s a fairly common disorder that about affects about four percent of adults, according to the American Academy of Sleep Medicine.
Scientists still aren’t sure what happens in the brain of a sleepwalker out for a stroll, but lead author Regis Lopez and his team believe that the state disrupts the brain’s pain sensors as well as consciousness.
Previous studies have shown that people feel less pain the deeper into sleep they drift and it’s possible that the same neural circuitry that causes sleepwalking may also affect how people feel pain, Mole reports. In order for the brain to sense pain, it has to decode signals from whatever part of the body is hurting.
But as sleep scientist Michele Terzaghi, who was not involved in the study, tells Mole, it’s possible that when sleepwalkers are up and about, that circuit could be weakened or completely severed. Even so, why chronic sleepwalkers often report feeling more pain when awake, remains unclear.
There is still much to learn about sleepwalking, but this study could provide new guidelines for taking care of sleepwalkers, as they could seriously injure themselves without waking up. In the meantime, chronic sleepwalkers may want to take extra care to protect themselves in case they start wandering about in the middle of the night.