A new study, published in Nature Neuroscience, examined how emotional memories may or may not be able to be targeted and manipulated during sleep.  Current literature supports the proposition that sleep can strengthen memory for emotional information.  Researchers in this study wanted to determine whether emotional memories could be specifically targeted and manipulated.  This study exposed human subjects to olfactory contextual fear conditioning and re-exposure during sleep to promote stimulus-specific fear extinction.  The researchers observed parallel changes in the brain’s hippocampal activity and organization of patterns in the amygdala. They conclude that it may be possible to target fears during sleep in order to enhance the process of overcoming fears.

According to the Washington Post, sleep reinforces certain memories and a large portion of the memory formation process takes place during sleep.  The study created fears in the participants by showing them a face, associating an odor, and delivering a painful electric shock.  This was a conditioning process to make them fear that face.  After a few rounds of conditioning, the participants became afraid of the face, and the smell acted as a cue associated with that face.  Researchers were able to use the odor to trigger fear memories during sleep.

The researchers have not yet attempted this procedure on preexisting fears.  However, it is theoretically possible to use the same procedure if they were able to create a connection between a phobia and a distinct odor.  Most likely, the first types of patients that would be appropriate for this fear reconditioning would be those that already have an odor associated with their fear.  For example, victims of gun crimes or soldiers back from war might have their fears triggered by the smell of gunpowder.

Fear is a type of emotional memory that is often learned at a young age through experience or observation.  For example, a child that sees his parent attacked by a dog or a child that is bitten by a dog learns to fear dogs.  In general, across all species, learning a fear is a quicker process than overcoming a fear.  Repeated exposure to the object of fear results in reformulating memories of that object in the context of safety.  Using a fear of spiders as an example, repeated exposure would involve first looking at photos of spiders, then observing a real spider housed in a faraway cage, followed by petting one with a thick glove, and finally by holding one.