Nightmares, haunted and unpleasant dreams while sleeping may have been experienced by almost all of us. This ends up grabbing your brain with fear and giving you anxiety and uneasiness.

Overcoming that fear can take a long time, but now researchers are saying it can be done in your sleep. US researchers suggest smells could be used to calm fears while sleeping.

According to the scientists at Northwestern University, fear levels can be lowered in human by using certain odors that triggers and rechannelizes frightening memories into harmless ones during a deep slumber.

It’s the first time that emotional memory has been manipulated in humans during sleep, researchers said.

Study

People were trained to associate two images, linked to smells, with fear. During sleep they were exposed to one of those smells and when they woke they were less frightened of the image linked to that smell.

The researchers carried study on 15 healthy human subjects. They were received mild electric shocks while seeing two different faces. They also smelled a specific odour while viewing each face and being shocked, so the face and the odour both were associated with fear.

Then, when a subject was asleep, one of the two odoures was re-presented, but in the absence of the associated faces and shocks.

This occurred during slow wave sleep when memory consolidation is thought to occur. Sleep is very important for strengthening new memories, said Hauner.

“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.

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.

The finding potentially offers a new way to enhance the typical daytime treatment of phobias through exposure therapy by adding a nighttime component.

“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,” said Hauner.

The study was published in the journal Nature Neuroscience.