research studies hypnosis

SYSTEMATIC REVIEW article

Meta-analytic evidence on the efficacy of hypnosis for mental and somatic health issues: a 20-year perspective.

• 1 Institute of Psychosocial Medicine, Psychotherapy and Psychooncology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
• 2 Department of Psychology and Neuroscience, Baylor University, Waco, TX, United States

Introduction: Documented use and investigation of hypnosis spans centuries and its therapeutic use has received endorsement by multiple medical associations. We conducted a comprehensive overview of meta-analyses examining the efficacy of hypnosis to provide a foundational understanding of hypnosis in evidence-based healthcare, insight into the safety of hypnosis interventions, and identification of gaps in the current research literature.

Methods: In our systematic review, meta-analyses of randomized controlled trials on the efficacy of hypnosis in patients with mental or somatic health problems compared to any control condition published after the year 2000 were included. A comprehensive literature search using Medline, Scopus, PsycINFO, The Cochrane Library, HTA Database, Web of Science and a manual search was conducted to identify eligible reviews. Methodological quality of the included meta-analyses was rated using the AMSTAR 2 tool. Effect estimates on various outcomes including at least three comparisons ( k  ≥ 3) were extracted and transformed into a common effect size metric (Cohen’s d ). If available, information on the certainty of evidence for these outcomes (GRADE assessment) was obtained.

Results: We included 49 meta-analyses with 261 distinct primary studies. Most robust evidence was reported for hypnosis in patients undergoing medical procedures (12 reviews, 79 distinct primary studies) and in patients with pain (4 reviews, 65 primary studies). There was a considerable overlap of the primary studies across the meta-analyses. Only nine meta-analyses were rated to have high methodological quality. Reported effect sizes comparing hypnosis against control conditions ranged from d  = −0.04 to d  = 2.72. Of the reported effects, 25.4% were medium ( d  ≥ 0.5), and 28.8% were large ( d  ≥ 0.8).

Discussion: Our findings underline the potential of hypnosis to positively impact various mental and somatic treatment outcomes, with the largest effects found in patients experiencing pain, patients undergoing medical procedures, and in populations of children/adolescents. Future research should focus on the investigation of moderators of efficacy, on comparing hypnosis to established interventions, on the efficacy of hypnosis for children and adolescents, and on identifying patients who do not benefit from hypnosis.

Clinical Trial Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023395514 , identifier CRD42023395514

1 Introduction

A systematic review of reviews can provide an expanded view and broad examination of a body of information available for a certain topic ( Hartling et al., 2012 ). Such reviews can highlight the evidence base for treatments with delineation of consistency, discrepancies, safety concerns, and efficacy ( Aromataris et al., 2014 ; Faulkner et al., 2022 ). This type of generalized information is often used in the development of treatment guidelines and recommendations.

We conducted such an overview of reviews (also called “umbrella review”; Gates et al., 2022 ) focusing on meta-analyses that have been published in the last 20 years on the efficacy of hypnosis in various clinical fields. Our overview and the meta-analyses included herein are important for clinical hypnosis to be added to treatment guidelines and recommendations as an evidence-based approach. This type of achievement has recently been realized by clinical hypnosis as the North American Menopause Society (NAMS) recommends it with Level-I status (good and consistent scientific evidence), as a nonhormonal treatment to manage menopause-associated vasomotor symptoms ( North American Menopause Society, 2023 ).

The documented use and investigation of hypnosis spans centuries and its therapeutic use has received endorsement by multiple medical associations ( British Medical Association, 1955 ; Council on Mental Health, 1958 ; Palsson et al., 2023 ). According to APA Division 30 (Society of Psychological Hypnosis), hypnosis is defined as a “state of consciousness involving focused attention and reduced peripheral awareness characterized by an enhanced capacity for response to suggestion” ( Elkins et al., 2015 , p. 6). This definition was finalized after several iterations, due to the challenges of defining hypnosis when the mechanisms are complex and have been found in biological (e.g., functional connectivity, brain states), psychological (e.g., expectancy, hypnotizability), and social (e.g., rapport, demand characteristics) domains with no primary factor and variable combinations of factors across applications ( Jensen et al., 2015 ). Hypnotherapy includes the therapeutic application of hypnosis, defined as the “use of hypnosis in the treatment of a medical or psychological disorder of concern” ( Elkins et al., 2015 , p. 7). The past several decades have yielded helpful research findings from investigations on the therapeutic use of hypnosis to treat a variety of somatic and mental concerns.

Over the past 20 years, the field of clinical hypnosis has seen an improvement in scientific rigor and new research has expanded to include randomized control trials and meta-analyses alike. A past systematic review of meta-analyses ( Häuser et al., 2016 ) highlighted the safety and efficacy of hypnosis within medicine and found robust evidence for the use of hypnosis to reduce pain, emotional distress, duration of medical interventions, medication use, and symptoms related to irritable bowel syndrome. The authors indicate that helping patients learn and use self-hypnosis techniques can empower them to participate more in their treatment and enhance their autonomy. Hypnosis techniques were also identified to help build trust between patients and providers and many of these techniques do not require a formal hypnotic induction to be effective. Although some research has pointed out potential unwanted effects associated with hypnosis ( Gruzelier, 2000 ), the authors’ conclusion regarding hypnosis as a safe intervention is consistent with a 2018 analysis of frequencies of adverse events in registered clinical trials which reported that there was zero report of a serious adverse event attributable to hypnosis and that the rate of “other adverse events” was 0.47% across 429 participants included in the studies ( Bollinger, 2018 ). Further evidence of this is provided in a large meta-analysis on hypnosis for pain relief which included 3,632 patients across 85 trials concluding that hypnosis is both a safe and effective alternative to pharmaceutical approaches ( Thompson et al., 2019 ).

A recent international survey that included nearly 700 hypnosis practitioners ( Palsson et al., 2023 ) provides a general view of how hypnosis is utilized in clinical settings. Results from the survey revealed that hypnosis is most commonly used by clinical psychologists (42.7% of respondents reported this as their profession) and 60.5% of respondents reported offering hypnosis treatment in a private practice setting. Respondents were also asked to rate the effectiveness of specific applications of clinical hypnosis. Seven applications of hypnosis were rated as “highly effective” by at least 70% of respondents: stress reduction, enhancing well-being, preparing for surgery, anxiety, mindfulness, childbirth, and enhancing confidence. Conversely, the applications with the least amount of endorsement for being highly effective included obsessive-compulsive disorder, eating disorders, and weight loss. Almost two-thirds of respondents reported using video conferencing to provide hypnosis intervention and the majority of those professionals rated remote delivery to be as effective as in-person delivery. It is important to note that some have critiqued the survey in its effort to gather information about the “hypnosis styles” commonly used by respondents’ which had overlapping response options and unclear intention ( McCann, 2023 ).

The recently published Evidence-Based Practice in Clinical Hypnosis ( Milling, 2023 ) provides a helpful resource that outlines the evidence and use of hypnosis for issues such as depression, anxiety, pain, and smoking cessation. In the introductory chapter ( Lynn and Green, 2023 ), the authors delineate what clinical hypnosis looks like in practice. More specifically, they describe that it usually begins with “prehypnotic information” characterized by inquiring about beliefs and previous experience with hypnosis, correcting misconceptions, discussing goals and potential suggestions, instilling positive expectancy, and answering any questions. This is typically followed by the hypnotic induction which conventionally includes instructive suggestions for eye fixation and closure, attention to breathing, calmness, and relaxation. After that, clinicians usually provide suggestions for “deepening” which focuses on intensifying and expanding the relaxation and feelings of calmness. This is traditionally followed by the hypnotic suggestions that deliberately aim to evoke a helpful emotional, psychological, and/or physiological experience based on the goals of treatment. Posthypnotic suggestions (those that elicit behavioral or mental activity after hypnosis) are often provided before re-alerting patients to normal consciousness.

A recent turning point in hypnosis research occurred in 2021 when the National Center for Complementary and Integrative Health (NCCIH) issued three funding opportunity announcements for mind-body intervention trials, and identified hypnotherapy as a treatment approach with “high programmatic priority” ( National Center for Complementary and Integrative Health, 2021a , b , c ). These funding mechanisms are consistent with the NCCIH strategic plan to pursue research that “[fosters] research on health promotion and restoration, resilience, disease prevention, and symptom management;” a top priority of the center ( National Center for Complementary and Integrative Health, 2021d ). Notably, these are the first grant opportunities issued by the NCCIH since 2015 to identify hypnotic interventions as a high priority research topic. The NCCIH recognizes evidence for the efficacy of hypnosis in the treatment of IBS, chronic pain, PTSD, and hot flashes ( National Center for Complementary and Integrative Health, 2020 ). The NCCIH website also notes preliminary data for the use of hypnosis in smoking cessation and anxiety related to medical and dental procedures.

While there is extensive evidence regarding the efficacy of hypnosis for various mental and somatic concerns, its generalized efficacy is not clearly understood. We were interested in investigating the broad efficacy of hypnosis interventions on various problem-relevant outcomes compared to non-active or active control groups as reported in meta-analyses of randomized controlled trials which are considered to be at the top of the evidence hierarchy ( Guyatt et al., 1995 ) and provide a foundational component of evidence-based healthcare. To our knowledge, this is the first overview of meta-analyses that summarizes relevant findings for clinical hypnosis. Hunt et al. (2018) suggested that overviews such as this can help filter the breadth of available information to improve decision making in healthcare and inform accurate development of treatment recommendations. We find this endeavor worthwhile to bring a greater awareness of hypnosis-specific interventions and to provide both researchers and clinicians a “user-friendly” overview of hypnosis research to more easily understand how clinical hypnosis can help, its overall safety, and in what areas more research is warranted.

2 Materials and methods

The reporting of this overview of reviews was guided by the standards of the Preferred Reporting Items for Overviews of Reviews (PRIOR) Statement ( Gates et al., 2022 ).

2.1 Eligibility criteria

According to our a-priori review protocol (PROSPERO International prospective register of systematic reviews, registration number CRD42023395514), we considered the inclusion of meta-analyses synthesizing results from randomized controlled trials (RCTs) only, in addition to those reporting effects of RCTs in subgroup analyses. Eligible reviews included patients with mental or somatic health problems of any age demographic. Reviews on experimental studies were excluded. Meta-analyses needed to either focus explicitly on hypnosis or report effects of a hypnosis intervention in subgroup analyses. Any non-active or active control group was considered as eligible comparator. Analyses reporting pooled effect estimates had to be based on at least three comparisons ( k  ≥ 3). Inclusion was limited to reviews published after the year 2000 to ensure a higher chance of systematic and more rigorous meta-analytic methods, transparent and complete reporting of methods and results, and risk of bias judgement of the included studies ( Moher et al., 1999 ).

2.2 Information sources and search strategy

A comprehensive literature search was conducted in MEDLINE, Scopus, PsycINFO, The Cochrane Library (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Methodology Register), Health Technology Assessment Database, and Web of Science (science and social science citation index). Within these databases, the search strategy included terms relating to or describing the intervention (hypnosis or hypnotherapy) and the study design (meta-analysis). There were no language restrictions, but an English abstract was required. The last search was conducted on 09.03.2023. The full MEDLINE search strategy is presented in Supplementary material 1 . We adapted the search strategy used in MEDLINE to run properly in the other electronic databases. Further, we validated our search by verifying whether all trials reported in comprehensive yearly reviews of published meta-analyses and RCTs on the effectiveness of clinical hypnosis and hypnotherapy (published 2014–2021 in the German journal “Hypnose-ZHH” by Maria Hagl) were included. In addition, we conducted a manual search in the reference lists of the included reviews.

2.3 Selection process

Two authors (AH and JR) jointly decided whether a systematic review met the inclusion criteria of this overview of reviews. In case of redundant publications of the same study, only one publication was considered for inclusion and the overlap was noted.

2.4 Data collection process

Descriptive data of the reviews was extracted by one author (AH) who was previously trained. Initially, extracted information of a subset of five reviews was checked by another author (JR) who had extensive coding experience to calibrate data extraction and to ensure fidelity with the codebook.

Overlap in the included primary studies was identified by generating a studies-included-per-review matrix. Updates of existing reviews were marked as such. We did not exclude previous versions of updated meta-analyses to recognize scientific progress. If various publications of the same dataset were identified, only one publication was considered for inclusion, and we report this duplicate publication.

Outcome data was extracted by one author (JR) with extensive experience in meta-analytic effect size coding. Effect sizes were extracted per comparison and outcome, regardless of primary study overlap across the reviews. We used standardized mean differences (Cohen’s d ) with 95% confidence interval to display differences between hypnosis and control conditions, applying the interpretation guideline of Cohen (1992) , regarding 0.20, 0.50, and 0.80 as small, medium, and large effect sizes, respectively. Positive effect sizes indicate a superiority of the hypnosis condition, while negative effect sizes suggest a superiority of the comparison condition. If outcome data were reported in different effect size formats (e.g., odds ratio), we transformed it into Cohen’s d by using Comprehensive Meta-Analysis (Biostat) software.

2.5 Data items

We extracted the following data items from the included reviews: descriptive characteristics of the meta-analyses (and their included primary studies), data to inform risk of bias assessment of the meta-analyses (and their included primary studies), quantitative outcome data, and certainty of evidence for important outcomes [e.g., heterogeneity of results, Grading of Recommendations, Assessment, Development and Evaluation (GRADE) assessments; Guyatt et al., 2008 ]. Data selection and coding were realized by two independent raters (AH and JR). Disagreements were resolved by consensus discussion. When necessary, a third researcher (CA) was consulted. If information on an aggregate level was missing in the included reviews, we checked the descriptions of the primary studies as reported in the reviews.

2.6 Risk of bias assessment

Methodological quality of the included meta-analyses was appraised and rated using the second edition of A MeaSurement Tool to Assess systematic Reviews (AMSTAR 2; Shea et al., 2017 ). The AMSTAR 2 is comprised of 16 domains (seven critical and nine noncritical) that allow for rating beyond a dichotomous “yes” or “no” to provide one of four overall ratings of confidence in the results of the review: high, moderate, low, and critically low. The critical domains included inquiries on protocol preregistration, adequacy of literature search, justification for exclusions, risk of bias, meta-analytic methods, interpretation of results, and publication bias. Meta-analyses in the present study were first rated on the seven critical domains because the presence of one or more critical flaw would result in an unchangeable rating of low (one critical flaw with or without non-critical weaknesses) or critically low (more than one critical flaw with or without non-critical weaknesses), respectively. Meta-analyses that did not have any critical flaws were rated on the other nine non-critical domains to earn an overall rating of moderate (more than one non-critical weakness) or high (no or one non-critical weakness), respectively.

2.7 Synthesis methods

Results were summarized graphically using a common effect size metric (standardized mean difference, Cohen’s d ). We did not synthesize the results of the reviews because of the diversity of populations, comparators, and outcomes and the considerable overlap of the primary studies across the included reviews.

2.8 Reporting bias assessment

Reporting bias considered in the included reviews (i.e., potential publication bias in the review results) was assessed using item 15 of the AMSTAR 2 tool ( Shea et al., 2017 ). Two independent raters (CA and JR) assessed whether the authors of the included meta-analyses carried out an adequate investigation of publication bias (small study bias) and discuss its likely impact on the results of the review. Disagreements were resolved by consensus discussion.

2.9 Certainty assessment

For each comparison and outcome, we extracted information on the certainty for the body of evidence [i.e., GRADE assessments ( Guyatt et al., 2008 )] if it was reported in the included reviews. We also collected specific information on the inconsistency of results, which is commonly reported by indicators of heterogeneity ( Higgins et al., 2003 ).

3.1 Systematic review selection

Our comprehensive search in various relevant data bases resulted in a total of 3,389 records. Of these, 2,723 duplicate and ineligible records were excluded. We screened 666 records, and after exclusion during abstract screening, 290 records remained and were screened for eligibility via full-text inspection. Of these, 241 reports were excluded due for reasons such as duplicate publication or failure to meet the inclusion criteria. Finally, 49 reviews were included in the present synthesis ( Figure 1 ; Supplementary material 2 ). Studies that appeared to meet the inclusion criteria but were excluded during the selection process are presented in Supplementary material 3 .

Figure 1 . PRIOR flow diagram ( Gates et al., 2022 ).

3.2 Characteristics of the systematic reviews

The 49 included meta-analyses were published between 2003 and 2022 and comprised 261 primary studies (published between 1962 and 2021). Twelve reviews (including 79 distinct primary studies) focused on medical procedures (e.g., surgery, needle-related procedures, etc.), five reviews were on labor and childbirth (10 primary studies), four reviews examined hypnosis for patients with pain (65 primary studies), and another five reviews focused on cancer (26 primary studies). We also identified 10 reviews on irritable bowel syndrome (19 primary studies), one review on obesity (16 studies), four reviews on smoking cessation (14 studies), and five were on patients with symptoms of mental/psychosomatic disorders (including insomnia; 37 primary studies). Additionally, we included three comprehensive reviews (112 primary studies) on various disorders. These reviews reported effects pooled across all studies and outcomes, but also yielded subgroup data for specific problems. Characteristics of the included meta-analyses are presented in Table 1 (more details are provided in Supplementary Table S1 ). The number of included hypnosis trials per review ranged from three ( Smith et al., 2003 ; O’Toole et al., 2016 ) to 57 ( Flammer and Bongartz, 2003 ). The number of patients included in the primary studies of the reviews ranged from 94 ( O’Toole et al., 2016 ) to 4,269 ( Holler et al., 2021 ), with a median of 502 (interquartile range 253 to 1,409). The majority of the reviews ( n  = 32, 65.3%) included adults only. In four reviews (8.1%), only children and/or adolescents were considered, 11 reviews (22.4%) included patients of all ages, and two reviews did not report information on the age of the study population. Of the 49 reviews, 18 (36.7%) included RCTs on hypnosis only, 23 (46.9%) focused on RCTs on different interventions and reported subgroup results for hypnosis, and eight reviews (16.3%) included randomized and non-randomized studies on hypnosis and reported subgroup results for RCTs. Seventeen reviews provided information on the assessment of hypnotizability within the primary studies. In eight of these reviews, results on the relationship between hypnotizability and outcome were reported (more or less detailed; Supplementary Table S1 ). Hypnosis was compared against various non-active and active control groups, predominantly against treatment as usual control groups (36 meta-analyses, 73.5%), attention control/placebo (31, 63.3%), active control/alternative treatment (17, 34.7%), waitlist control conditions (16, 32.7%), and no treatment control groups (13, 26.5%, see Table 1 ; Supplementary Table S1 ).

Table 1 . Characteristics of the included systematic reviews.

3.3 Primary study overlap

There was a considerable overlap of primary studies across the included systematic reviews ( Supplementary Figure S1 ). Each primary study was included in M  = 2.21 (SD = 1.77) reviews. Of the 261 distinct primary studies, 129 (49.4%) were considered in only one review, while some studies were included in several reviews: Lindfors et al. (2012) was included in 10 reviews; Moser et al. (2013) and Liossi et al. (2006) were included in 9 reviews, Katz et al. (1987) , Lang et al. (2000) and Liossi and Hatira (2003) were each included in 8 reviews ( Supplementary Table S2 ).

3.4 Risk of bias in systematic reviews

The assessment of the methodological quality of the included reviews using the AMSTAR 2 tool ( Shea et al., 2017 ) revealed only a few overall quality ratings of high . The methodological quality of nine reviews (18.4%, including three of four reviews on smoking cessation) was judged as high, indicating no weaknesses in critical domains. One review was assessed as having moderate overall quality due to two non-critical weaknesses and low overall quality was judged for 13 reviews (26.5%), indicating one critical flaw with or without non-critical weaknesses. Of these low quality reviews, nine did not provide a list of excluded studies and justified the exclusions, three did not assess the presence of a publication bias and discuss its likely impact on the results, and one review did not register an a-priori review protocol. A majority of 26 reviews (53.1%) had a methodological quality judged as critically low (i.e., having more one critical flaw with or without non-critical weaknesses). Figure 2 shows a summary of the quality assessment of the included reviews. Results of the AMSTAR 2 assessment on the critical items and an overall rating for the included studies are shown in Supplementary Table S3 .

Figure 2 . Quality assessment of the included reviews showing overall ratings of the AMSTAR 2 tool. Each circle represents one included review, and the number in circles are studies included in each review. Order of circles is from high quality (left) to low quality (right).

3.5 Summary of results

We extracted i  = 118 effect sizes from the included reviews. Effect sizes (Cohen’s d ) were based on M  = 9.19 primary studies including M  = 796 patients, and ranged from d  = −0.04 to d  = 2.72 ( Figures 3 – 5 ). More than half of the effects ( i  = 75, 63.6%) were reported as significant. According to Cohen (1992) , about one third of the effects ( i  = 41, 34.7%) can be regarded as small, 25.4% ( i  = 30) as medium, and 28.8% ( i  = 34) as large.

Figure 3 . Effect sizes for comparing hypnosis against control conditions in patients undergoing medical procedures or labor/childbirth. Colored areas indicate different effect size interpretation as negative (red), very small/ d  < 0.2 (yellow), and small/ d  ≥ 0.2, medium/ d  ≥ 0.5, or large effects/ d  ≥ 0.8 (green). Attention, attention control; ICU, intensive care unit; TAU, treatment as usual.

Figure 4 . Effect sizes for comparing hypnosis against control conditions in patients with pain, cancer, or irritable bowel syndrome. Colored areas indicate different effect size interpretation as negative (red), very small/ d  < 0.2 (yellow), and small/ d  ≥ 0.2, medium/ d  ≥ 0.5, or large effects/ d  ≥ 0.8 (green). Blank cells indicate missing information. Attention, attention control; CBT, cognitive-behavioral therapy; NoT, no treatment control; SM, symptom monitoring; TAU, treatment as usual; WL, waitlist control.

Figure 5 . Effect sizes for comparing hypnosis against control conditions for smoking cessation, obesity, patients with psychological/psychosomatic symptoms or somatic complaints, and for various disorders. Colored areas indicate different effect size interpretation as negative (red), very small/ d  < 0.2 (yellow), and small/ d  ≥ 0.2, medium/ d  ≥ 0.5, or large effects/ d  ≥ 0.8 (green). Blank cells indicate missing information. Attention, attention control; CBT, cognitive-behavioral therapy; NoT, no treatment control; TAU, treatment as usual; WL, waitlist control.

3.5.1 Medical procedures

Reviews on patients undergoing medical procedures made up the largest number of our synthesis ( n  = 12). In these reviews, 34 effect sizes were reported ranging from d  = 0.1 to d  = 2.53, 28 effect sizes were significant, 17 can be interpreted as small, five as medium, and nine as large effects. The largest effects appeared in populations of children with needle-related pain and distress ( Uman et al., 2006 ; Birnie et al., 2018 ), with effect sizes between d  = 1.07 and d  = 2.53. Homogeneously across all reviews, (very) small effects were seen for physiological parameters, procedure time, and recovery. Medium to large effects appeared for mental distress including anxiety, except for one review ( Zeng et al., 2022 ) that reported a small effect ( Figure 3 ).

3.5.2 Labor and childbirth

Five reviews examined hypnosis in labor and childbirth, reporting 19 effect sizes ranging from d  = −0.04 to d  = 1.16. Eighteen effect sizes were positive, but only four proved to be significant. Among the reported effects, four were small, five were medium, and another five were large. For the outcome “use of pharmacological pain relief,” the largest effects appeared (five effect sizes; all but one medium to large and significant). The majority of effects on other birth-related outcomes were (very) small and not significant ( Figure 3 ).

Effects on hypnosis in patients with various types of clinical pain including fibromyalgia were examined in five reviews (one reported effects within a subgroup analysis; Ramondo et al., 2021 ). Seven positive effect sizes (six significant, three each small or medium, one large) were reported, ranging from d  = 0.37 to d  = 0.81 ( Figure 4 ). Six effects were reported for pain (intensity), and one review reported results for the reduction of sleep problems ( d  = 0.81; Zech et al., 2017 ).

3.5.4 Cancer

Eleven positive effect sizes ( d  = 0.43 to d  = 2.72) coming from six reviews were reported for nausea and vomiting, pain, and anxiety in cancer patients. Nine effects were significant (no information on the significance of the remaining two effects), one each can be interpreted as small or medium, and nine effects were large (including all effects on pain and anxiety; Figure 4 ).

3.5.5 Irritable bowel syndrome

A group of 10 reviews examined the use of hypnosis for patients with irritable bowel syndrome. Effects were reported for gastrointestinal symptoms, but also for other issues that accompany the disease, e.g., pain, diarrhea, constipation, bloating/distension, mental distress, anxiety and depression, and health-related quality of life. For most of these outcomes, hypnosis revealed small ( i  = 11) or medium effects ( i  = 8). Only one effect size was large (abdominal pain; Lee et al., 2014 ). Range of effects was from d  = 0.02 to d  = 0.83, and eight of the 15 effects were significant ( Figure 4 ).

3.5.6 Smoking cessation

Five reviews (including three Cochrane reviews) compared hypnosis for smoking cessation to various control groups. Altogether, six effects were reported, ranging from d  = 0.12 to d  = 0.84 ( Figure 5 ). Only two effects were significant. Two effects fell into the range of small effects, and one each was medium or large.

3.5.7 Obesity

We included two reviews focusing on obesity reporting six effect sizes (range d  = 0.09 to d  = 1.58; Figure 5 ). In comparison to treatment as usual, attention control, or no treatment conditions, significant, large effects emerged for weight loss at post-treatment and follow-up. When hypnosis combined with cognitive-behavioral therapy (CBT) was compared to CBT alone, effects on weight loss were (very) small at post-treatment but increased to significant large effects at follow-up.

3.5.8 Symptoms of mental/psychosomatic disorders

In seven reviews, nine effect sizes were reported for reduction of symptoms of mental or psychosomatic disorders. The effects ranged from d  = 0.06 to d  = 1.58, one effect was small, three were medium, and four were large. All effects were significant, except one non-significant null effect on anxiety symptoms when hypnosis in addition to CBT was compared to CBT alone ( Figure 5 ).

3.5.9 Various disorders

Moreover, one review ( Flammer and Bongartz, 2003 ) reported a significant medium effect size of d  = 0.64 for hypnosis in patients with somatic complaints on various outcomes. Three comprehensive reviews on hypnosis for various disorders pooled the effects of all included studies ( Flammer and Bongartz, 2003 ; Eason and Parris, 2019 ; Ramondo et al., 2021 ). The four reported effect sizes were significant and ranged from d  = 0.25 to d  = 1.28. One can be regarded as small, two as medium, and another one as large.

3.5.10 Harms or unintended effects of hypnosis

Eight of the 49 included reviews stated that no adverse events or side effects were reported in any of the included primary studies. One review ( Schaefert et al., 2014 ) reported, that in one primary study one patient complained of slight dizziness after the first hypnosis session but continued the therapy, while in another study one dropout due to a panic attack during a hypnosis session was mentioned. In the review of Lam et al. (2015) , only one study reported the incidence of adverse events, which was seen in the control group receiving zolpidem. The meta-analysis of Noergaard et al. (2019) considered “reduction in adverse events” as an outcome. Seven studies reported data, the pooled effect was in favor of hypnosis, but non-significant ( RR  = 0.61). In two reviews of hypnosis in labor and childbirth, there were two ( Madden et al., 2012 ) or three primary studies ( Madden et al., 2016 ) that reported data on any adverse events (i.e., maternal side effects, newborn resuscitation), but no significant differences between hypnosis and control groups were found. In two primary studies included in the review of Barnes et al. (2019) , data on adverse events were reported without revealing any statistically significant difference between the hypnosis and control groups. The remaining 28 reviews did not include information on the safety of hypnosis ( Supplementary Table S1 ).

3.5.11 Moderators of efficacy

Reviews including n  ≥ 10 studies were inspected for the reporting of moderator effects on the efficacy of hypnosis, potentially yielding sufficient statistical power to detect moderator effects in meta-regression or subgroup analyses. Results are summarized in Supplementary Table S4 .

Various patient characteristics were examined in the reviews for their potential impact on the efficacy of hypnosis. Two reviews ( Schnur et al., 2008 ; Chen et al., 2017 ) found significantly higher mean effect sizes in studies with children than in trials with adult populations, while Flammer and Alladin (2007) did not demonstrate differential effects based on age. Results on the impact of participants’ sex is mixed. One review reported significantly larger effects for studies with participants of mixed-sex compared to female-only populations ( Chen et al., 2017 ). In contrast, another review could not find any differences between subgroups (male, female, mixed; Flammer and Alladin, 2007 ). In the review of Chen et al. (2017) , significantly larger effects were found in studies with hematological malignancy than in trials with patients suffering from a solid tumor and for studies with procedure-related stressors compared to no such stressors. In reviews including patients undergoing surgery, neither effects of anesthesia (local, general; Tefikow et al., 2013 ; Holler et al., 2021 ), nor type of surgery (diagnostic procedure vs. other, Kekecs et al., 2014 ; Holler et al., 2021 ) could be found. Two reviews examined the impact of hypnotizability on treatment outcome, reporting medium ( r  = 0.31, Flammer and Alladin, 2007 ; r  = 0.44; Flammer and Bongartz, 2003 ) and large correlations ( r  = 0.53; Milling et al., 2021 ) between hypnotizability and outcome.

Moderator analyses of characteristics of the hypnosis intervention included formal aspects of the intervention (format, setting, presentation mode, dose, frequency) and characteristics of the hypnosis intervention itself (type of hypnosis, standardization, use of direct suggestions). Neither format (hypnosis provided individually vs. in groups; Flammer and Alladin, 2007 ; Krouwel et al., 2021 ) nor setting (inpatients, outpatients, mixed; Flammer and Alladin, 2007 ) had an impact on the efficacy of hypnosis. Moderator analyses on the mode of presentation yielded significantly larger effects for live presentations in comparison to audio recorded presentations ( Schnur et al., 2008 ; Kekecs et al., 2014 ). However, this was not the case in two other reviews ( Tefikow et al., 2013 ; Holler et al., 2021 ). Results on the impact of dose on treatment outcome are also mixed. While two reviews found significant advantages for participants receiving more treatment time ( Krouwel et al., 2021 ; Ramondo et al., 2021 ), two other reviews did not yield results to support differential effects of an intervention based on the dose (brief, medium, long; Tefikow et al., 2013 ; Holler et al., 2021 ). Moreover, there was no difference of frequency on outcome; weekly sessions produced effects similar to sessions less than once weekly; ( Krouwel et al., 2021 ).

In the review of Flammer and Alladin (2007) , type of hypnosis was demonstrated to be a moderator variable. “Modern hypnosis” was significantly more effective than classical hypnosis and mixed-forms of hypnosis. Furthermore, the impact of self-hypnosis, direct suggestions, and standardization was tested. Hypnosis was significantly more effective when it combined therapist delivery with self-hypnosis compared to self-hypnosis only ( Chen et al., 2017 ) and hypnosis interventions had significantly larger effects when incorporating self-hypnosis than when self-hypnosis was not included ( Milling et al., 2018 ). Studies that incorporated direct suggestions, i.e., suggestion directly addressing the primary outcome pain, did not produce larger effects than trials which did not use such suggestions ( Milling et al., 2021 ). Additionally, Holler et al. (2021) found no effects of standardization of hypnosis.

Characteristics of the control group did not influence the size of reported effects, as similar results were reported for hypnosis compared to standard care and to attention control conditions ( Schnur et al., 2008 ; Tefikow et al., 2013 ; Holler et al., 2021 ).

Finally, characteristics of the included primary studies had an influence on the reported effect size of hypnosis. In one review, sample size was significantly and inversely correlated with effect size ( Schnur et al., 2008 ), another review found significantly larger effects for studies conducted in Europe than in trials conducted in America ( Chen et al., 2017 ).

3.6 Reporting biases

In 37 of the included meta-analyses (75.5%), the authors carried out an adequate investigation of publication bias (small study bias) and discussed its likely impact on the results ( Supplementary Table S3 ).

3.7 Certainty of evidence

Only few included reviews reported the certainty in the body of evidence. High certainty was reported only for two effects (self-reported pain, hypnosis vs. standard care, and vs. attention control; Jong et al., 2020 ). Certainty was moderate for five effects (pain intensity at post-treatment, hypnosis vs. control; Langlois et al., 2022 ; postoperative pain, postoperative anxiety, procedure time, and postoperative nausea and vomiting, hypnosis vs. control; Zeng et al., 2022 ). For four effects, the certainty of evidence was rated as low (spontaneous vaginal birth, hypnosis vs. control; Madden et al., 2016 ; smoking cessation, hypnosis vs. attention-matched behavioral treatments; Barnes et al., 2019 ; pain intensity follow-up and pain interference with daily activities, hypnosis vs. control; Langlois et al., 2022 ), and for five effects it was judged as very low (smoking cessation, hypnosis vs. no smoking cessation support; Hartmann-Boyce et al., 2021 ; self-reported pain, self-reported distress, and behavioral measures of distress, hypnosis vs. control; Birnie et al., 2018 ; use of pharmacological pain relief/anesthesia, hypnosis vs. control; Madden et al., 2016 ). Information on the inconsistency of results was reported more frequently in the reviews ( i  = 95, 80.5% of the extracted effect sizes). If reported, heterogeneity was low ( I 2  ≤ 50%) or significant for about one third of the effects ( i  = 32, 33.7%), in two thirds it was substantial ( I 2  > 50%) and/or significant ( i  = 63, 66.3%).

4 Discussion

With this systematic review of meta-analyses, we aimed at investigating the efficacy of clinical hypnosis interventions on various problem-relevant outcomes compared to non-active or active control groups. Through a comprehensive search in relevant databases, we identified 49 meta-analyses which were comprised of 261 distinct randomized controlled trials. Hypnosis interventions were examined for various mental and somatic health concerns and included adult populations as well as children and adolescents. The findings reported in the included meta-analyses underline the potential of hypnosis to positively impact various mental and somatic treatment outcomes. Specifically, more than half of the results were at least of medium effect size, and only one negative effect was reported (in fact, it was a null effect; d  = −0.04). The most robust evidence was demonstrated in studies involving patients undergoing medical procedures with 12 reviews including 79 distinct primary studies, and in patients with pain (four reviews, 65 primary studies). The largest effects were seen for hypnosis in populations of children/adolescents, however, only four reviews focused on the efficacy of hypnosis specifically in children and/or adolescents. Of the 11 other meta-analyses that included children/adolescents and adult populations, one review supported the larger effects of hypnosis in children than in adults ( Schnur et al., 2008 ), while two other meta-analyses did not find differences ( Flammer and Alladin, 2007 ; Chen et al., 2017 ). The findings also demonstrated a substantial heterogeneity of primary study results in about two thirds of the reported effects, which clearly limits the generalizability of the findings and points to the need of exploring the variance in results via moderator analyses ( Thompson, 1994 ). While most of the included meta-analyses did not involve a sufficient number of primary studies to allow for moderator analyses ( Hedges and Pigott, 2004 ), nine meta-analyses investigated the impact of patient, intervention, and control group characteristics on the outcome of hypnosis ( Flammer and Bongartz, 2003 ; Flammer and Alladin, 2007 ; Schnur et al., 2008 ; Tefikow et al., 2013 ; Kekecs et al., 2014 ; Chen et al., 2017 ; Milling et al., 2018 , 2021 ; Ramondo et al., 2021 ). Overall, the moderator analyses tested a variety of potential impact factors but revealed mixed results. The only consistent evidence was reported for hypnotizability, which had medium to large positive effects on the outcome of hypnosis and supports findings of a meta-analysis on the impact of hypnotizability in clinical care settings ( Montgomery et al., 2011 ). More specifically, 34 effects from 10 studies and 283 participants revealed statistically significant correlation ( r  = 0.24), indicating that greater hypnotizability was associated with greater effects of hypnosis interventions.

This synthesis led to the identification of some limitations of the evidence from the included systematic reviews and their primary studies. First, there is a large overlap of primary studies across the included reviews hampering an unbiased meta-synthesis of the reported effects. Second, heterogeneity of findings across the primary studies in the included reviews is mostly substantial, rendering it difficult to draw general conclusions and make clear recommendations for clinical practice. Third, a considerable number of effects is based on a very low number of studies/comparisons which negatively impacts the precision of the meta-analytic results ( Brand and Bradley, 2016 ) and the possibility to examine moderator effects ( Hedges and Pigott, 2004 ). Third, not only is the number of studies included in a considerable number of meta-analyses low, but also the number of patients per study. On the one hand, meta-analysis is advantageous in enhancing the precision of single studies by combining multiple findings to generate a pooled estimate ( Finckh and Tramèr, 2008 ). On the other hand, if only a few (small) studies are included in an overall effect size, the precision of meta-analytic results may, nevertheless, be low ( Guyatt et al., 2011 ). Fourth, most of the included reviews pooled their effects across various types of control groups (i.e., passive and active control groups), making it difficult to provide clear recommendations for clinical practice. Fifth, results of the included meta-analyses provided only sparse evidence on direct comparisons to other established interventions/interventions that have been proven efficacious (e.g., head-to-head comparisons). Finally, safety data were reported only in less than half of the reviews. To make a balanced decision about the use of hypnosis, it is essential to have comprehensive evidence on both benefits and harms. Therefore, systematic harm monitoring and reporting should become standard in RCTs of behavioral interventions ( Klatte et al., 2023 ).

The results of our overview should be interpreted by considering some limitations of the review methods used. We did not calculate overall effects across the reported estimates, considering the substantial overlap of primary studies included in the meta-analyses. We further did not include the risk of bias within and across the primary studies as reported in the meta-analyses. Internal validity was assessed by using the Cochrane risk of bias tool ( Higgins et al., 2011 ; Sterne et al., 2019 ) in most reviews (see Supplementary Table S1 ), but its impact on the effects was analyzed and reported not consistently in all reviews. Similarly, publication bias was not systematically examined in the included meta-analyses, potentially due to an insufficient number of primary studies to run tests for funnel plot asymmetry (with k  < 10 the assessment methods are not very reliable; Dalton et al., 2016 ).

Our overview of meta-analyses carries various implications for clinical practice and for future research. Altogether, there is reasonable evidence from primary studies and systematic reviews that hypnosis can be an efficacious treatment option for patients with mental and somatic health problems. Although effects were heterogeneous for many outcomes, nearly all (99.2%) were positive, and the majority of effects was at least of medium effect size. Taking into account that clinical hypnosis is usually applied as a low-dose intervention, the results are promising. Hypnosis revealed the largest effects in children and for patients undergoing medical procedures. Because children and adolescents are often viewed as having higher average hypnotic ability than that of adults, it seems sensible that younger patients with mental or somatic health issues may be more responsive to hypnotic suggestions than adult patients ( Accardi and Milling, 2009 ). Large effects of hypnosis in patients undergoing medical procedures might be driven by the patient-provider context and the idea that medical settings are especially conducive for responding to suggestions ( Cheek, 1962 ; Varga, 2013 ).

Two of the included reviews focused on the effect of hypnosis in combination with CBT ( Milling et al., 2018 ; Ramondo et al., 2021 ). The results suggest that hypnosis might have an additional impact when used as an adjunct to CBT, and the largest effects were seen when the hypnotic treatment directly integrated CBT principles into the hypnosis ( Ramondo et al., 2021 ).

Our comprehensive overview also aimed at identifying research gaps to guide future research. In the light of our findings, we encourage hypnosis researchers to examine moderators of efficacy and to contribute further knowledge to the question: What works for whom and under which circumstances? We also emphasize the need for studies directly comparing hypnosis to established interventions that have been proven efficacious and to extend the knowledge basis on the effectiveness of hypnosis for children and adolescents. Finally, to allow for a balanced interpretation of benefits and harms of hypnosis and to derive clear recommendations for using hypnosis in various settings, harmful and unintended effects of hypnosis have to be explicitly and comprehensively assessed within future RCTs, transparently and completely reported in the respective publications, and should be considered in the reporting of subsequent meta-analyses.

5 Conclusion

This systematic review of meta-analyses provides a broad overview of the substantial evidence supporting the use of clinical hypnosis to treat a range of mental and somatic health issues. The vast majority (99.2%) of outcomes demonstrated positive effects, with over half exhibiting at least a medium effect size. Notably, the largest effects were found when hypnosis was used with child/adolescent patient populations, to treat pain, and to aid medical procedures. The review also revealed important limitations, including substantial heterogeneity in study outcomes which warrants a call for more studies directly comparing hypnosis to established interventions. Greater awareness for assessing adverse events in efficacy research on hypnosis is needed. Overall, these findings support the use of hypnosis in clinical practice and mental health professionals and medical providers are thus encouraged to consider the use and referral of hypnosis interventions, especially for patients undergoing medical procedures, those experiencing pain, and when working with children.

Data availability statement

The data analyzed in this study is subject to the following licenses/restrictions: the data that support the findings of this study are available from the corresponding author upon reasonable request. Requests to access these datasets should be directed to [email protected] .

Author contributions

JR: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Visualization, Writing – original draft. CA: Data curation, Investigation, Visualization, Writing – original draft, Writing – review & editing. AH: Data curation, Formal analysis, Investigation, Writing – original draft.

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. Publication fees for this article were provided by the open access publication fund of the Thuringian University and State Library (ThULB).

Acknowledgments

The authors kindly thank Ernil Hansen for his advice on early stages of this work and Maria Hagl for her comprehensive yearly reviews of the published meta-analyses and RCTs on hypnosis and hypnotherapy that served as a validation basis for the search strategy used in this study.

Conflict of interest

JR is a member of the scientific board of the Milton H. Erickson Society Germany (M.E.G., since 10/22) and has received travel reimbursements for talks at the meetings of the M.E.G.

The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary material

The Supplementary material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpsyg.2023.1330238/full#supplementary-material

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Keywords: hypnosis, hypnotherapy, meta-analysis, randomized controlled trial, efficacy

Citation: Rosendahl J, Alldredge CT and Haddenhorst A (2024) Meta-analytic evidence on the efficacy of hypnosis for mental and somatic health issues: a 20-year perspective. Front. Psychol . 14:1330238. doi: 10.3389/fpsyg.2023.1330238

Received: 30 October 2023; Accepted: 12 December 2023; Published: 08 January 2024.

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*Correspondence: Jenny Rosendahl, [email protected]

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What is hypnosis and how might it work?

Ann williamson.

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Email: [email protected]

Collection date 2019.

This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License ( http://www.creativecommons.org/licenses/by-nc/4.0/ ) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages ( https://us.sagepub.com/en-us/nam/open-access-at-sage ).

Hypnosis can be seen as ‘a waking state of awareness, (or consciousness), in which a person’s attention is detached from his or her immediate environment and is absorbed by inner experiences such as feelings, cognition and imagery’. 1 Hypnotic induction involves focusing of attention and imaginative involvement to the point where what is being imagined feels real. By the use and acceptance of suggestions, the clinician and patient construct a hypnotic reality.

Everyday ‘trance’ states are part of our common human experience, such as getting lost in a good book, driving down a familiar stretch of road with no conscious recollection, when in prayer or meditation, or when undertaking a monotonous or a creative activity. Our conscious awareness of our surroundings versus an inner awareness is on a continuum, so that, when in these states, one’s focus is predominantly internal, but one does not necessarily lose all outer awareness.

Hypnosis could be seen as a meditative state, which one can learn to access consciously and deliberately, for a therapeutic purpose. Suggestions are then given either verbally or using imagery, directed at the desired outcome. This might be to allay anxiety by accessing calmness and relaxation, help manage side effects of medications, or help ease pain or other symptoms. Depending on the suggestions given, hypnosis is usually a relaxing experience, which can be very useful with a patient who is tense or anxious. However, the main usefulness of the hypnotic state is the increased effectiveness of suggestion and access to mind/body links or unconscious processing. Hypnosis can not only be used to reduce emotional distress but also may have a direct effect on the patient’s experience of pain. 2

Hypnosis in itself is not a therapy, but it can be a tool that facilitates the delivery of therapy in the same way as a syringe delivers drugs. Hypnosis does not make the impossible possible, but can help patients believe and experience what might be possible for them to achieve.

Hypnotic states have been used for healing since humankind has existed, but because hypnosis can be misused for so-called entertainment and has been portrayed in the media as something mysterious and magical, supposedly out of the hypnotic subject’s control, it has been viewed with distrust and scepticism by many health professionals. However, recent advances in neuroscience have enabled us to begin to understand what might be happening when someone enters a hypnotic state, 3 – 8 and evidence is building for the use of hypnosis as a useful tool to help patients and health professionals manage a variety of conditions, especially anxiety and pain.

Landry and colleagues 9 and Jensen and Patterson 10 give good and comprehensive information on recent research into the neural correlates of hypnosis. The study of hypnosis is complex and many factors such as context, expectation and personality affect hypnotic response as well as the suggestions used.

As clinicians, we know that simply knowing something cognitively does not necessarily translate into being able to control emotions such as fear and anxiety. A simple ‘model’ that can be used to help patients understand that this is quite a usual response is that of right/left brain, which can also correlate with conscious/unconscious and intellectual/emotional processing.

From the diagram, it can be seen that to communicate effectively to both types of our processing, we need more than words; we need to use words that evoke imagery. It is no surprise, therefore, that all the greatest teachers use metaphor, parable and story to convey their teachings.

The brain has two cerebral hemispheres, and while in our normal waking state, the left brain tends to be more dominant and could be likened to our ‘conscious mind’. This communicates verbally and is the more intellectual, conscious and rational part of ourselves. When we relax or become deeply involved in some activity, our right brain becomes more dominant. The right brain could be seen to be the more emotional, creative part of ourselves that communicates with symbols and images, and could be seen as our ‘unconscious mind’. There is always a difficulty in telling ourselves not to be upset or anxious because words are not the language of the right brain. But one can paint a word picture using guided imagery or metaphor.

While this description may oversimplify the neural processing of the left and right hemispheres, it is a useful way to explain hypnosis to patients.

Neuroimaging research has demonstrated that subjective changes in response to suggestion are associated with corresponding changes in brain regions related to the specific psychological function in question. 11 , 12 When someone imagines something in hypnosis (colour, sound, physical activity and pain), recent neuroscience findings show us that similar areas of the brain are activated as when the person has that experience in reality. Derbyshire and colleagues 13 showed that both physically induced and hypnotically induced pain are accompanied by activations in areas associated with the classic ‘pain matrix’. Similar findings have been shown with visual and auditory suggestions. 14 , 15

When patients are highly anxious, they are operating at an emotional, rather than cognitive level, and one can engage and direct their creative imagination towards what is useful for them. Anxious patients are using their imagination to create possible catastrophic scenarios, which generates even more anxiety and hence more adrenaline, which can then spiral into panic.

Patients may feel that they are being overwhelmed by their emotions, but if the health professionals can engage their attention, direct their imagination to feeling calm or to re-experience some positive past experience or activity and give positive suggestions, then the patients will start to feel calmer and more able to cope.

To enter hypnosis, one needs to focus attention (this is done during a hypnotic induction), and there are many ways to achieve this. A candle flame or a computer screen could be a visual focus. An auditory focus could be music, chanting or using mantras. Induction could be mainly kinaesthetic, such as in progressive muscular relaxation (PMR) or could use ‘involuntary’ (or ideomotor) movement. One of the simplest methods is to engage the patient’s imagination using revivification (or re-experiencing) of an experience, a daydream or fantasy. Hypnosis can be used formally in a therapeutic session or informally in conversation by directing the patient’s focus and engaging their imagination.

Patients can then be taught self-hypnosis, which means they can enter this state deliberately at will, to utilise imagery and suggestion to help themselves. 16 In the clinical setting, the health professional wants to avoid dependence and save time and money, and studies have shown that hypnotic interventions can be very cost-effective. 17 Montgomery and colleagues 18 randomised control trial of 200 breast cancer patients using a 15-min session of hypnosis or structured attention to control side effects after surgery also showed reduced medical costs with the hypnosis intervention.

There is a strong case for more research in the field of hypnosis in palliative care, where mind-body interventions are increasingly accepted as part of comprehensive excellent cancer care (even in large cancer centres that once focused only on drug trials).

Hypnosis research takes place in laboratory conditions and usually compares results between ‘highs’ and ‘lows’; in other words, those who are highly hypnotisable and those who are not. It has been shown that hypnotisability is a genetic trait and follows a Gaussian or bell-shaped distribution, so most research into hypnotic responding focuses on 10% of the population. In the clinical context, we have to work with everyone, and even if hypnosis is not used in a formal way, it can inform one’s approach to the patient and the language used. For experimental purposes, the procedure must be standardised and all variables controlled as much as possible. In the clinical context, hypnosis is tailored to the individual patient and their responses, and the motivation is very different from the laboratory situation.

Although there is increasing evidence for the usefulness and cost-effectiveness of using hypnosis in a wide variety of conditions, it is difficult to get funding for hypnosis because of a shortage of randomised control trial support (the gold standard so beloved of Trusts, CCGs, research funders and all clinical trialists). In a Catch-22 situation, one of the major difficulties in undertaking any hypnosis research in the United Kingdom is lack of funding. One major factor in this is the World Health Organization classification of hypnosis as a ‘Complementary Therapy’. This puts hypnosis in the same category as various other approaches of dubious scientific credibility and effectively bars researchers into hypnosis obtaining funding. Also, much hypnosis is done by individual clinicians in a private practice, a community setting or as an individual in a department.

There is no statutory regulation of hypnosis training or practice in the United Kingdom, and many organisations offer training, which may be of varying quality.

There are three professional bodies in the United Kingdom, the Hypnosis and Psychosomatic Section of the Royal Society of Medicine, the British Society of Medical & Dental Hypnosis (Scotland) for doctors and dentists and the British Society of Clinical & Academic Hypnosis (BSCAH), which consist entirely of qualified health professionals [mostly working within the National Health Service (NHS)]. The British Society of Clinical & Academic Hypnosis ( www.bscah.com ) runs training courses in hypnosis for health professionals that range from 1-day introductory workshops for different specialties, through a 6-day foundation training, which equips one to utilise hypnotic techniques within one’s field of expertise, to a fully accredited University Diploma with City of Birmingham University.

BSMDH (Scotland) and BSCAH are also constituent members of the European and International Societies of Hypnosis. The European Society of Hypnosis ( www.esh-hypnosis.eu ) consists of 41 Constituent Societies in 20 countries throughout Europe, with over 14,800 members from the fields of Medicine, Dentistry, Psychology and allied health care professions. The International Society for Hypnosis (ISH; www.ishhypnosis.org ) is the world headquarters for researchers and clinicians interested in hypnosis. ISH serves as the umbrella and meeting place for its members and 33 (still growing) Constituent Societies from around the world.

If, as clinicians, we want to prove the effectiveness of hypnosis, then we need to show that the degree of improvement and speed of achieving this is enhanced by hypnosis. We need practice-based evidence. One way of doing this is to compare results obtained by those using hypnosis with those of people who do not use hypnosis. If large numbers of us were to use a simple questionnaire, both at the start and end of our work, and pool our results centrally, then this would provide a large amount of data that could go some way to resolving this. The proposed questionnaire would be MYMOP (Measure Your Own Medical Outcome Protocol: http://www.bris.ac.uk/primaryhealthcare/resources/mymop/ ).

The BSCAH is trying to facilitate and support this project; so, if you are interested please contact us at www.bscah.com . For any technical queries, you can contact Dr Peter Naish at [email protected] .

Funding: The author received no financial support for the research, authorship and/or publication of this article.

Conflict of interest statement: The author declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

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