Fear calmed during sleep: New Study shows that this possibility after fear was reduced in people by repeatedly exposing them to the fear memory during sleep, according to a study published online Sunday in the journal Nature Neuroscience.

In a study that included 15 healthy young adults who received mild electric shocks while viewing two faces, they were exposed to an odor when seeing each face and getting a shock to see if fear can be calmed during sleep. The face and odor were associated with fear, according to Katherina Hauner, who conducted the research when she was a postdoctoral fellow in neurology at the Northwestern University Feinberg School of Medicine in Chicago.

When a subject was sleeping, an odor was continuously presented but without the associated faces and shocks. As soon as the subjects woke up, they were shown both faces. Their fear reactions were lower for the face linked to the odor they smelled during their rest, thus explaining Hauner's theory that the fear is calmed during sleep.

"It's a novel finding," Katherina Hauner, the study's lead author told USA Today. "We showed a small but significant decrease in fear. The bigger picture is that, perhaps, the treatment of phobias can be enhanced during sleep."

There may be an advantage to adding a nighttime component to exposure therapy, a treatment for phobias and post-traumatic stress disorder, Hauner said. She is also the assistant director of the Cognitive Neuroscience Laboratory at the Rehabilitation Institute of Chicago.

This exposure therapy that was used is a way to study fear without the risk of anxiety increasing.

"This is a new area of research," she said.

"The study is important and exciting because it's a reminder that sleep doesn't just improve or consolidate memory," Mark Mahowald, an American Academy of Neurology member who was not involved in the research said. "It can extinguish memories. "The extinction of memory during sleep could be important for people with PTSD and chemical dependencies. Further research could look at relapse prevention."