You are getting sleepy, very sleepy … but why? “Hypnosis is the oldest Western form of psychotherapy, but it’s been tarred with the brush of dangling watches and purple capes,” says David Spiegel, MD, professor and associate chair of psychiatry and behavioral sciences. “In fact, it’s a very powerful means of changing the way we use our minds to control perception and our bodies.”
Spiegel is the senior author of a new study, published online in July in Cerebral Cortex, showing which areas of the brain have altered activity during hypnosis. The researchers used functional magnetic resonance imaging to observe the brains of 57 subjects — 36 who were highly hypnotizable and 21 who were quite the contrary. They saw three changes in the highly hypnotizable group while those subjects were under guided hypnosis, but not while they were at rest or recalling a memory.
First, they saw a decrease in activity in an area called the dorsal anterior cingulate, part of the brain’s salience network. “In hypnosis, you’re so absorbed that you’re not worrying about anything else,” Spiegel says.
Second, they saw an increase in connections between two other areas of the brain — the dorsolateral prefrontal cortex and the insula. Spiegel describes this as a brain-body connection that helps the brain process and control what’s going on in the body.
Last, the researchers observed reduced connections between the dorsolateral prefrontal cortex and the default mode network, which includes the medial prefrontal and posterior cingulate cortex. This likely represents a disconnect between people’s actions and their awareness of their actions, Spiegel says — which may allow them to engage in activities suggested by a clinician, or that they suggest to themselves, without being self-conscious about doing so.
In highly hypnotizable individuals, hypnosis has been shown to reduce pain, treat addiction, and ease anxiety, phobias or post-traumatic stress disorder. The new findings might help scientists develop treatments for the rest of the population — those who aren’t naturally as susceptible to hypnosis.
“We’re certainly interested in the idea that you can change people’s ability to be hypnotized by stimulating specific areas of the brain,” Spiegel says.