Face Your Fear and Sleep It Out - How Sleeping Promotes Fear Extinction

Helen Holmes October 10, 2019

 The standard treatment for phobia is exposure therapy, in which the source of fear is shown to the patient several times until he or she experiences a reduction in phobic symptoms. This therapy however, seemed to be more effective when followed by sleep, a new study suggests.

The study, led by Edward Pace-Schott, a clinical instructor in psychology at the Harvard Medical School, with the help of Rebecca M.C. Spencer from the University of Massachusetts, looked on the value of sleep in treating people suffering from arachnophobia, commonly known as fear of spider. Their goal was to determine whether or not fear extinction, an active process of creating a new emotional memory in which the source of fear is no longer considered as fearsome, is affected by sleep, wakefulness, and time of day (morning or evening). 66 undergraduate women were recruited to join the study. Researchers added ‘morning’ and ‘evening’ control groups in order to check whether the time of day has an effect to fear extinction.

Exposure Therapy and Sleep

The participants were divided into 6 groups – sleep, wake, morning and evening. Each group were asked to watch a YouTube video featuring a spider for 14 times, as a standard exposure therapy. The video was designed to take away the irrational fears about spiders, leaving the patients less afraid. The control groups watched the videos for 2 hours apart from the morning and evening, while the sleep and wake groups 12 hours apart.

In 60% of the viewings, participants were startled by the loud noise. The researchers gauge the startle response by measuring palm sweat using a sensor. They had several series of viewings and the researchers continued to track their progress.

They found that sleep, is indeed helpful in addressing phobia. According to Pace-Schott, sleep helped mellow the women’s fears by strengthening the formation of new memories during the exposure therapy. Women who slept 12 hours at night showed lower levels of phobic symptoms. They had reduced heart rate and feeling of unpleasantness, disgust, and fear. Those who stayed awake for 12 hours had the opposite response. They had more sweats and increased phobic symptoms as compared to those who slept for 12 hours, even if they watch the videos for several times. In fact, the ‘awake’ group found the spider to be even more frightening.  

Promoting Fear Extinction through Sleep

In what specific stage in sleeping does processing of emotional memory takes place? Pace-Schott pointed out that the positive effects of sleeping are generated during the rapid eye movement (REM) stage – period where most dreaming occurs. During this phase, a network of emotional brain regions is activated, which in turn overlap the regions affected by anxiety disorders. It’s possible that REM is reprocessing the emotional memory, Pace-Schott suggests. In previous research, it was found that people deprived of sleep find it difficult to generate fear extinction memories after undergoing exposure therapy. According to the researchers, the REM is the stage in which fear extinction is strengthened and stabilised.

The study suggests that exposure therapy could be more effective when performed before bedtime. However, there’s a downside in this approach, Pace-Schott pointed out. ‘People are more reactive to fear in the evening’. Exposure therapy may then cause them insomnia. The better way to take advantage of the positive effects of sleeping in treating phobia even during day time is to let patients take a nap after the exposure therapy, he added.