Fear may be the most powerful of all human emotions, but according to a study released today in the journal Nature Neuroscience, sleep can be its enemy.
Specific emotional memories of human beings were deliberately altered during sleep in a new research experiment.
The study found that sending a sensory cue associated with a fear to a sleeping person could significantly reduce that fear when the person was awake and facing the source of their fear.
Fifteen people looked at pictures of faces while they were monitored for skin conductance (sweat) and their brains were imaged in an fMRI machine.
The conditioning within this experiment actually worked. The skin conductance measures and fMRI images showed that the test subjects did indeed learn to fear the faces and aromas that often came with a shock.
After the test subjects woke up, they were again exposed to the pictures of faces in the same set up as before, in the fMRI machine. This time, however, their fear of the specific face associated with the odor they’d been given while asleep was diminished. The longer they slept in slow wave mode, and the longer they smelled the aroma, the more powerful the effect.
Their fear of the other face, on the other hand, remained unchanged.
This is extremely exciting,” Edward Pace-Schott, an assistant professor of psychiatry at Harvard Medical School who often uses spiders to study fear acquisition and extinction, told NBC News. “While it’s hard to interpret, it suggests that if you can get contextual information into the brain during sleep, some sort of learning process can take place. The fact that it gets into the brain during sleep is remarkable.”
Incorporating this technique into any kind of therapy may be a long way off, but Pace-Schott suggested it eventually may be possible to use odors as a supplement to waking exposure therapy to boost fear extinction memory.