Researchers of a new study used day-time exposure theory, used to cure phobias to treat fear memories while sleeping.
Fear memories while sleeping often result in nightmares and disrupted sleep. In a new study, researchers from the Northwestern University Feinberg School of Medicine found that this problem can be tackled. This is the first time researchers have provided evidence that suggests manipulating human emotional memory during sleep.
Exposure therapy is a common treatment for phobia. It includes exposing a person to his fear frequently so that he overcomes that fear. The treatment was first used in the 1950s by South African psychologists and psychiatrists and later was also introduced in England. Researchers have termed this form of treatment to be the most effective for anxiety disorders too. Researchers presented findings where this typical daytime treatment of phobias was used to treat the same at night while sleeping.
"It's a novel finding," said Katherina Hauner, a postdoctoral fellow in neurology at Northwestern University Feinberg School of Medicine. "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."
For the new study, researchers examined 15 healthy individuals who received mild electric shocks while seeing two different faces. They also smelled a specific odorant while viewing each face and being shocked, so the face and the odorant both were associated with fear. Subjects received different odorants to smell with each face such as woody, clove, new sneaker, lemon or mint.
Later, the participants were subjected to one of the odorants while asleep. This time the odorant was not accompanied by either the face or mild shocks. When the subjects woke up, they were exposed to both faces. When they saw the face linked to the smell they had been exposed to during sleep, their fear reactions were lower than their fear reactions to the other face.
"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.
The study will be published Sept. 22 in the journal Nature Neuroscience.
