A new study suggests that constant exposure to fear memory while sleeping may help a person reduce that fear when he wakes up. Scientists believe that their findings may help people suffering from phobias and traumas.
Katherine Hauner, co-author of the study from Northwestern University Feinberg School of Medicine, and his colleagues called the process improved “exposure therapy” with nighttime component.
Exposure therapy is a technique used in treating anxiety disorders commonly used on patients suffering from post-traumatic stress disorder (PTSD) and phobias. Patients are exposed to their object of fear or context under supervision of a trained therapist in order for them to get over it.
"It's a novel finding," said Katherina Hauner in a press release. "We showed a small but significant decrease in fear. If it can be extended to pre-existing fear, the bigger picture is that, perhaps, the treatment of phobias can be enhanced during sleep."
The researchers recruited 15 participants and administered mild electric shocks while seeing two faces and smelling odorants such as woody, clove, new sneaker, lemon or mint. The faces and odorants were associated to their fears.
After the first phase, the participants were put into slow wave sleep. This is the time when memory consolidation occurs. The participants were exposed to one of the two odorants used in phase one.
"While this particular odorant was being presented during sleep, it was reactivating the memory of that face over and over again which is similar to the process of fear extinction during exposure therapy," Hauner said.
As soon as they wake up, the patients felt lesser fear on the face associated to the odor they smelled during their sleep.
The researchers measured fear by measuring the presence of sweat in the skin and brain scan. The brain scan confirmed that there were changes in the brain activity, specifically on the hippocampus region where memory is stored and the amygdala associated with emotions, before and after the exposure therapy.
The study was published in the Sept. 22 issue of the journal Nature Neuroscience.