Uncovering the new science of clinical hypnosis

Years ago, as a psychology grad student, Amanda Barnier, PhD, did a pair of experiments in which she gave people a pile of stamped postcards and asked them to send her one each day for the next few months. She asked a group of people to mail the cards as a favor to her; for another group, she administered a posthypnotic suggestion to send the cards. Both groups were equally likely to mail the cards, day after day, until their stacks ran out. But their motivations and experiences, she found, were quite different ( Psychological Science , Vol. 9, No. 4, 1998 opens in new window). The people she asked to do her a favor had an internal explanation for the action. “They felt they made a decision to comply with my social request,” said Barnier, now professor of cognitive science and pro vice-chancellor of research performance and development at Macquarie University in Australia. “The hypnotized people felt it was a compelling urge they had to meet. Hypnosis made the action feel more involuntary.”

That reduced sense of personal agency may be precisely what makes clinical hypnosis such a powerful tool in psychotherapy and behavior change, said Barnier, who has studied the power of hypnosis ever since. “By changing the person’s sense of authorship, the effort becomes external to them. Hypnosis kick-starts the process by making it easier to change.”

Hypnosis is as old as the field of psychotherapy itself, but today, advocates pointing to its evidence base say it deserves a fresh look—and a much wider audience. “Hypnosis has a certain historical mystique that can sometimes make it difficult for practitioners to understand its modern relevance,” said David Godot, PsyD, a clinical psychologist in Long Beach, California, and president of APA’s Division 30 (Society of Psychological Hypnosis). In fact, clinical hypnosis has clear benefits in psychotherapy, improving outcomes in areas such as pain management, anxiety, depression, sleep, and more. “Over the past few decades, there have been tremendous advances in understanding hypnosis and its benefit for research and practice,” Godot said.

[Related: Hypnosis training and certifications]

Division 30 defines hypnosis as “a state of consciousness involving focused attention and reduced peripheral awareness characterized by an enhanced capacity for response to suggestion” (Elkins, G. R., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 63, No. 1, 2015opens in new window). Yet the definition of hypnosis has been the subject of debate for the better part of a century. While some experts believe hypnotic induction results in an altered state of consciousness, others argue it’s not so much a distinct state as a shift in attention. What experts on both sides of the debate agree on, however, is that hypnosis allows for a special kind of focused attention that opens people up to suggestion.

In hypnotherapy, a clinician starts with a hypnotic induction, spoken prompts that encourage the client to shift their focus and deepen relaxation. Then, the clinician provides therapeutic suggestions to guide the client toward the wanted change. “Our brains soak up information from the environment and combine it with our prior beliefs and experiences and memories to form a conscious experience of the moment,” said Afik Faerman, PhD, a postdoctoral fellow in clinical neuropsychology at Stanford University and president-elect of Division 30. “Hypnosis is one context during which our brain edits that conscious experience. As the facilitator of a hypnosis session, I can provide guidance about how to edit those experiences, but it’s up to that person to act on my suggestions.”

Those suggestions are what set hypnosis apart from meditation and mindfulness-based interventions. Both mindfulness and hypnosis are built on the backbone of focused attention; however, mindfulness aims for nonjudgmental awareness and acceptance. “Hypnotherapy has some important advantages,” said Guy Montgomery, PhD, a professor of psychology and director of the Center for Behavioral Oncology at the Icahn School of Medicine at Mount Sinai in New York City, who uses and studies clinical hypnosis for reducing pain in cancer patients. “Whereas meditation helps you accept a problem, hypnosis allows people to make changes to do something about the problem,” he said.

Research has shown evidence that posthypnotic suggestion can elicit striking changes in perception and behavior. Two classic—and colorful—studies illustrate the power of hypnotic suggestion. In one, Amir Raz, PhD, a cognitive neuroscientist at McGill University in Montreal, and colleagues showed that hypnosis could disrupt the Stroop effect, the popular laboratory task that instructs participants to name the font color of written words. People respond much slower and make more mistakes when these words are color names and the word and the font color are different and thus interfere with each other (for example, the word “blue” written in red font). But when highly hypnotizable participants were instructed under hypnosis to pay attention only to the font color and not the text, the Stroop interference effect disappeared ( Archives of General Psychiatry , Vol. 59, No. 12, 2002 opens in new window). The study has been replicated many times by multiple labs. One recent example showed that while hypnosis itself did not eliminate the Stroop effect, posthypnotic suggestion did—a finding confirmed by electroencephalogram (EEG) (Zahedi, A., et al., Neuropsychologia, Vol. 96, No. 1, 2017opens in new window). Such findings offer a vivid example of the ways that hypnosis can exert a top-down influence on cognition, even for automatic processes like reading.

In another experiment, David Spiegel, MD, a professor of psychiatry and behavioral sciences at Stanford University, and colleagues gave participants a suggestion to view color when looking at grayscale images. Brain scans showed that the color-processing regions of their brains lit up even though the photos in front of them contained nothing but shades of gray ( The American Journal of Psychiatry , Vol. 157, No. 8, 2000 opens in new window).

Both studies tested people considered “highly hypnotizable,” those who become hypnotized quickly and easily and respond strongly to hypnotic suggestions. Spiegel’s research suggests that people who are higher in hypnotizability have more functional connectivity—essentially, more communication—between the central executive network, which manages executive functions such as decision-making and working memory, and the salience network, which is tasked with prioritizing important incoming information (Hoeft, F., et al., Archives of General Psychiatry, Vol. 69, No. 10, 2012opens in new window). “We believe that the executive network of individuals who are high in hypnotizability has a greater ability to moderate where their attention goes during hypnosis,” said Faerman, a postdoctoral scholar in Spiegel’s lab.

Hypnotizability is a trait that follows a normal distribution: 10% to 20% percent of people aren’t very hypnotizable, and about the same proportion are highly responsive; everyone else falls somewhere in between. Several measures exist to assess a person’s potential to respond to hypnosis, such as the brief Hypnotic Induction Profile (Spiegel, H., & Spiegel, D., Trance and Treatment: Clinical Uses of Hypnosis, American Psychiatric Association Publishing, 2004opens in new window) or the Elkins Hypnotizability Scale (Kekecs, Z., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 69, No. 1, 2021opens in new window).

While responsiveness varies, however, most people can benefit from hypnosis to some degree, said Gary Elkins, PhD, ABPP, a professor of psychology and neuroscience at Baylor University. “People in the higher range may respond more quickly, but almost anyone can be a candidate for clinical hypnosis,” he said. “If people are in the lower range, they may just need more sessions or more practice to achieve the same results.”

Elkins’s research has indicated that clinical hypnosis may have benefits even in people who are not especially high in hypnotizability. In recent work, he’s tested a hypnotherapy intervention for treating hot flashes in menopausal women and breast cancer survivors. In one trial, menopausal women received five weekly sessions of clinical hypnosis or a structured-attention control intervention. Those in the hypnosis group reported hot flashes were reduced by more than 74%, whereas the control group reported a 17% reduction in hot flashes. Objective physiological monitoring of hot flashes supported their reports, showing a 57% reduction in hot flashes for women who had hypnosis compared with a 10% reduction for control participants ( Menopause , Vol. 20, No. 3, 2013 opens in new window).

Research suggests that hypnotic suggestion may be useful for a host of other behavioral health problems, including improving sleep, managing stress, and quitting smoking. One meta-analysis found, for instance, that hypnosis was a promising treatment for sleep problems (Chamine, I., et al., Journal of Clinical Sleep Medicine, Vol. 14, No. 2, 2018opens in new window). And a meta-analysis of hypnosis for depression found that hypnosis appears to be an excellent treatment option for depression (Milling, L. S., et al., American Journal of Clinical Hypnosis, Vol. 61, No. 3, 2019opens in new window).

Yet hypnosis is not a therapy in itself, Elkins and other clinicians stress. “Hypnosis is not a primary intervention. But it’s clear it has an important role to play as an adjunctive approach to psychotherapy,” Elkins said. And incorporating hypnosis into psychotherapeutic interventions might boost their benefit.

Research dating back 3 decades found that hypnosis could enhance the effectiveness of cognitive behavioral therapy (CBT). An updated meta-analysis showed that when the two were combined, they had a small-to-medium, but statistically significant, advantage over CBT alone for managing depression or pain (Ramondo, N., et al, International Journal of Clinical and Experimental Hypnosis, Vol. 69, No. 2, 2021opens in new window). Another analysis found that hypnosis was more effective in reducing anxiety when combined with other psychological interventions than when it was used alone (Valentine, K. E., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 67, No. 3, 2019opens in new window).

Some of the most robust evidence for clinical hypnosis is in controlling pain, as evidenced by two recent meta-analyses. The first assessed 85 controlled studies of experimentally evoked pain and found hypnosis delivered meaningful pain relief for most people, with the greatest effects in those who rated high on hypnotic suggestibility (Thompson, T., et al., Neuroscience & Biobehavioral Reviews, Vol. 99, 2019opens in new window). In a separate analysis, researchers assessed 42 controlled studies of hypnosis for treating clinical pain. They concluded that hypnosis is “very efficacious,” with a mean weighted effect size in the medium range (Milling, L. S., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 69, No. 3, 2021opens in new window).

“Hypnosis can help turn down the volume on pain, both acute and chronic,” Montgomery said. In his work with cancer patients, he has demonstrated its benefit in a series of clinical trials—including a forthcoming study suggesting that hypnosis could reduce the joint pain that is a common side effect of a drug used to treat breast cancer. His program has funding from the National Cancer Institute to provide free training to any cancer care providers who want to learn hypnosis to help patients manage pain.

“Hypnosis works. And the cool thing is that in our randomized trials, we don’t find effects due to race or ethnicity. This is something that can help anybody,” said Montgomery.

While researchers continue to build the evidence base for hypnosis, they’re also exploring what hypnosis can reveal about the brain. The picture that is emerging is complicated. Neuroimaging studies have found little consensus in pinpointing brain regions and networks involved in hypnotic states and suggestions. That makes sense considering the varied nature of hypnosis, said Devin Terhune, PhD, a cognitive neuroscientist at King’s College London. “If you look across the literature, some studies use hypnosis to induce visual hallucinations, others to modulate pain or memory. Given these very different phenomena, it’s not that surprising that we don’t find a single brain region or network involved in hypnotic suggestion,” he said.

Yet patterns are emerging. In a comprehensive review of the literature, Raz and colleagues found three key networks associated with hypnotizability and hypnotic response: the central executive network, the salience network, and the default mode network, which is associated with internal attention and mind-wandering. They also found involvement of the lingual gyrus, a region that plays a role in mental imagery (Landry, M., et al., Neuroscience & Biobehavioral Reviews, Vol. 81, Part A, 2017opens in new window).

The involvement of the default mode network makes sense with people’s experiences of hypnosis, said Michael Lifshitz, PhD, an assistant professor of psychiatry at McGill University and a coauthor of the review. “This network is really active when people are daydreaming. It’s as if they’re rehearsing their habitual thoughts about their place in the world. But activity in the default mode network seems to go down in hypnotic states,” he explained. “It’s almost as if you’re letting your usual ways of making sense of the world relax and soften, making space for something new to emerge.”

To dig deeper into the neurocognitive mechanisms of hypnosis, Faerman and Spiegel explored the link between hypnotizability and perseveration, the tendency to apply previously learned rules to new information, even when presented with a new and better rule. Perseveration can be thought of as a marker of cognitive inflexibility, and it draws on the same executive and salience networks implicated in hypnosis. They found people who are higher in hypnotizability tend to be lower on perseveration, more easily adopting new information that overrides previous knowledge. In other words, those who are more responsive to hypnotic suggestions appear to have more cognitive flexibility. Hypnotizability, they conclude, may share common cognitive mechanisms with evaluating errors and implementing logical rules ( Scientific Reports , Vol. 11, No. 5704, 2021 opens in new window).

But Terhune has found being highly hypnotizable could be “a double-edged sword.” His research uncovered a link between hypnotic suggestibility and higher rates of dissociative problems like functional neurological disorders and posttraumatic stress disorder ( Neuroscience & Biobehavioral Reviews , Vol. 139, 2022 opens in new window). “These seem to be individuals who have a capacity to modulate their awareness and perception in response to verbal suggestion. But because their subjective experience is so malleable, they may be more at risk of developing dissociative disorders in response to traumatic episodes,” Terhune said.

Much more work needs to be done to understand how hypnosis works, and for whom. But there are good reasons to press on. “If we can better understand how hypnosis works, we can actually design interventions to improve it or provide it in a more efficient way,” Faerman said. In a study forthcoming in Nature Mental Health, Faerman, Spiegel, and colleagues applied transcranial magnetic stimulation (TMS) to targeted brain regions in people with the central pain disorder fibromyalgia. Their goal was to inhibit the executive network and increase its functional connectivity with the salience network, mimicking the patterns seen in highly hypnotizable people.

The group that received TMS had significant increases in hypnotizability that were not seen in the group that received a sham TMS. The next step will be to see whether such an intervention may increase their response to hypnosis treatment, such as one designed to reduce pain. “This is just a proof of concept,” Faerman said. “But my vision for the future is that someday, a person can come in before their psychotherapy appointment to get a quick TMS session that will increase the effectiveness of hypnosis and improve treatment outcomes.”

Experts are also looking for ways to expand the reach of hypnotherapy. Spiegel has developed an app called Reveri to deliver hypnosis outside the clinic, for indications including improving sleep, managing pain, and reducing stress. Elkins is advising Mindset Health, which has developed the hypnotherapy app Finito for quitting smoking, Evia for managing symptoms of menopause, and Nerva for irritable bowel syndrome.

As these apps make hypnosis more accessible to the public, advocates say more psychotherapists should consider adding hypnosis to their own clinical skills. “Hypnosis is a loaded term, and people in professional settings are sometimes uncomfortable with it because of its association with entertainment,” Faerman said. “But not learning about it is a mistake for clinical psychology. This is a tool that can improve the lives of our patients in a safe and evidence-based way.”