The effects of hypnosis on heart rate variability

Non-pharmacological interventions for reducing dental anxiety in pediatric dentistry: a network meta-analysis

BACKGROUND

Child dental anxiety is a prevalent issue in the field of pediatric dentistry. At present, several non-pharmacological interventions are employed to mitigate anxiety during dental treatments for children. The objective of this study is to assess the effectiveness of diverse non-pharmacological interventions in reducing dental anxiety, as well as enhancing heart rate during pediatric dental treatments. To achieve this, we conducted a systematic review and a network meta-analysis (NMA) to compare the efficacy of various outcome indicators.

METHODS

A thorough search was conducted in the databases of PubMed, Embase, Web of Science, Cochrane Library, Scopus, APA PsycInfo, CINAHL, and AMED to identify all eligible randomized controlled trials (RCTs) from the beginning of the databases up to August 1, 2024. The quality assessment was carried out using the Cochrane Collaboration's bias risk tool. The two outcome measures under consideration were dental anxiety and heart rate. Network graphs, league tables and SUCRA were constructed using R 4.2.3 software and Stata 16 software. This study is registered in PROSPERO under the registration number CRD42023467610.

RESULTS

The study examined 12 different non-pharmacological approaches, drawing from a pool of 61 research studies involving 6,113 participants aged 4 to 16 years. The results of the network meta-analysis revealed that music (SUCRAs: 93.60%) proved to be the most effective measure in mitigating dental anxiety, followed by aromatherapy (SUCRAs: 78.58%) and game (SUCRAs: 70.99%). Moreover, hypnosis (SUCRAs: 98.80%), music (SUCRAs: 79.58%), and relaxation (SUCRAs: 72.41%) were identified as the top three interventions for decreasing heart rate.

CONCLUSION

In this NMA, when contemplating dental anxiety outcomes, music is recommended as a priority. For heart rate outcomes, hypnosis may be a preferred measure. However, owing to the limited number of articles, the conclusion of this study still requires additional confirmation or correction through more high-quality primary studies in the future.

"Close your eyes and relax": the role of hypnosis in reducing anxiety, and its implications for the prevention of cardiovascular diseases

Anxiety is the most common form of mental health disorder, affecting millions of people worldwide. Psychosocial interventions such as mindfulness and cognitive behavioral therapy (CBT) have been suggested as an effective treatment in the management of general anxiety and anxiety disorders, with emerging evidence also suggesting the effectiveness of hypnosis. Moreover, anxiety has shown to be linked to the onset and development of several cardiovascular diseases (CVD), which are the leading cause of global death. In this paper, we review the current literature to examine the role that anxiety has on the onset and development of CVD and summarize the current knowledge on the role that hypnosis and hypnotherapy have in reducing anxiety, also explaining how this can impact the cardiovascular system and the prevention of CVD. Review of the evidence suggests that hypnosis and hypnotherapy are effective in treating anxiety and may positively affect the heart and the cardiovascular system, reducing sympathetic activation and increasing parasympathetic tone, potentially preventing the onset of CVD related to increased sympathetic activation. However, further studies are required to further understand how hypnosis and hypnotherapy affect the cardiovascular system through investigation of the neurophysiological components of the hypnotic state and of the mind-body relationship. Healthcare systems should embed mental health screening in patients at risk of developing CVD as part of the clinical pathway and consider the role that hypnosis and hypnotherapy may play in the management of CVD.

Autonomic nervous system modulation during self-induced non-ordinary states of consciousness

Self-induced cognitive trance (SICT) is a voluntary non-ordinary state of consciousness characterized by a lucid yet narrowed awareness of the external surroundings. It involves a hyper-focused immersive experience of flow, expanded inner imagery, modified somatosensory processing, and an altered perception of self and time. SICT is gaining attention due to its potential clinical applications. Similar states of non-ordinary state of consciousness, such as meditation, hypnosis, and psychedelic experiences, have been reported to induce changes in the autonomic nervous system. However, the functioning of the autonomic nervous system during SICT remains poorly understood. In this study, we aimed to investigate the impact of SICT on the cardiac and respiratory signals of 25 participants proficient in SICT. To accomplish this, we measured various metrics of heart rate variability (HRV) and respiration rate variability (RRV) in three conditions: resting state, SICT, and a mental imagery task. Subsequently, we employed a machine learning framework utilizing a linear discriminant analysis classifier and a cross-validation scheme to identify the features that exhibited the best discrimination between these three conditions. The results revealed that during SICT, participants experienced an increased heart rate and a decreased level of high-frequency (HF) HRV compared to the control conditions. Additionally, specific increases in respiratory amplitude, phase ratio, and RRV were observed during SICT in comparison to the other conditions. These findings suggest that SICT is associated with a reduction in parasympathetic activity, indicative of a hyperarousal state of the autonomic nervous system during SICT.

An exploratory study of hypnosis-induced blood count changes in chronically stressed individuals

Hypnosis is a clinically accepted relaxation technique known for stress reduction. Results from hematological research provide evidence of changes in blood components through hypnosis. However, these hematological effects have been rarely examined. Hence, we exploratively investigated the effect of a single relaxation hypnosis on the hemogram in stressed individuals, assuming a reduction of leukocytes, thrombocytes, and erythrocytes (primary outcomes). Additionally, a reduction in the erythrocyte-related parameters (hemoglobin, hematocrit), and an increase in plasma volume was hypothesized (secondary outcomes). Forty-four either individuals (89 % women) with chronic stress and moderate to high hypnotic suggestibility were randomized to a hypnosis condition (20 min relaxation hypnosis; n = 20) or a control condition (20 min documentary; n = 24). Venous blood was drawn before and after the intervention and used to generate a differential hemogram and determine the plasma volume. The relaxation hypnosis led to a significant reduction in erythrocytes (Cohen's d=0.23) and consequently to a decrease in erythrocyte-related parameters (hemoglobin, d=0.27; hematocrit, d=0.37) as well as to a reduction in thrombocytes (d=0.15) in the hypnosis compared to the control condition. Putatively, this could be the consequence of an increased plasma volume (d=0.10), estimated by the hematocrit concentration and body weight. A hypnosis-induced change in leukocyte count could not be confirmed. Thus, a single session of relaxation hypnosis already alters specific blood count parameters. While relaxation-induced vasodilatation might explain these changes, it is still not completely clear how these changes affect our stress response system.

The Effects of a Single Relaxation Hypnosis Session on Mental Stress in Chronically Stressed Individuals

Abstract. Background: Chronically stressed people often suffer from anxiety and depressive mood. Hypnosis is a technique that can induce a relaxation response and reduce negative stress symptoms. Objective: This explorative study investigated the impact of a single relaxation hypnosis session on stress-related psychological symptoms. Method: 47 suggestible, stressed individuals (87 % female) were randomized to a hypnosis group ( n = 23, 20-minute hypnosis) or a control group ( n = 24, 20-minute scientific documentary). Before and after the intervention, we assessed perceived stress, negative affect, anxiety, and depressive mood. Results: After the hypnosis intervention, depressive mood ( d = 0.36) and state anxiety ( d = 1.00) decreased, while negative affect remained stable ( d = 0.04). Perceived stress was reduced in both groups. Conclusion: A single relaxation hypnosis session decreased stress-related symptoms in chronically stressed individuals. Our results substantiated the stress-alleviating effects of hypnosis.

Impact of hypnosis on psychophysiological measures: A scoping literature review

Exploring psychophysiological changes during hypnosis can help to better understand the nature and extent of the hypnotic phenomenon by characterizing its influence on the autonomic nervous system (ANS), in addition to its central brain effects. Hypnosis is thought to induce a relaxation response, yet studies using objective psychophysiological measures alongside hypnosis protocols show various results. We review this literature and clarify the effects of hypnosis on psychophysiological indices of ANS activity and more specifically of the stress/relaxation response, such as heart rate variability and electrodermal activity. Studies reporting psychophysical measures during hypnosis were identified by a series of Pubmed searches. Data was extracted with an interest for the influence of hypnotizability and effects of specific suggestions or tasks on the findings. We found 49 studies comprising 1315 participants, 45 concerning healthy volunteers and only 4 on patients. Sixteen compared high vs. low hypnotizable people; 30 measured heart rate, 18 measured heart rate variability, 25 electrodermal activity, and 23 respiratory signals as well as other physiological parameters. Globally, results converge to show reductions in sympathetic responses and/or increases in parasympathetic tone under hypnosis. Several methodological limitations are underscored, such as older studies (N = 16) using manual analyses, small sample sizes (<30, N = 31), as well as uncontrolled multiple comparisons. Nevertheless, we confirm that hypnosis leads to a physiological relaxation response and highlight promising avenues for this research. Suggestions are made for guiding future work in this field.

[Current applications of hypnosis in the field of cardiac electrophysiology]

With a growing acceptance of clinical hypnosis in medicine, new fields of application are being explored. Data from recent studies support the use of hypnosis for pain management during procedures, such as ablation of arrhythmias and implantation of subcutaneous implantable cardioverter defibrillators, management of preoperative anxiety and reduction of postoperative atrial fibrillation. The aim of this review article is to summarize the findings of investigations showing the application of hypnosis in the field of cardiac electrophysiology, to review the rationale for the efficacy of hypnosis in management of cardiac arrhythmias and to highlight possible future directions in clinical applications and scientific perspectives.

The effect of hypnotherapy on exam anxiety among nursing students

OBJECTIVES

This study examines the effect of hypnotherapy on exam anxiety among first-year nursing students. Nursing students have high tendency to experience stress and anxiety. Anxiety therapy which encompasses mind and body would be helpful for them.

METHODS

Sixty first-year nursing students participated in this interventional study. The hypnotherapy sessions started eight weeks prior to second exam. Outcome of hypnotherapy were assessed by measuring the exam anxiety score using TAI and clinical measurements (serum cortisol and vital signs). The measurements were done twice, there are two exams, where first exam and measurement were 1 day before exam (without hypnotherapy) and the second exam and measurement were 1 day before exam (with hypnotherapy).

RESULTS

The mean difference of exam anxiety score and serum cortisol level between pre and post hypnotherapy sessions was statistically significant.

CONCLUSIONS

This study found that hypnotherapy is an effective tool in the management of exam anxiety among the nursing students.

Bispectral Index Alterations and Associations With Autonomic Changes During Hypnosis in Trauma Center Researchers: Formative Evaluation Study

BACKGROUND

Previous work performed by our group demonstrated that intermittent reductions in bispectral index (BIS) values were found during neurofeedback following mindfulness instructions. Hypnosis was induced to enhance reductions in BIS values.

OBJECTIVE

This study aims to assess physiologic relaxation and explore its associations with BIS values using autonomic monitoring.

METHODS

Each session consisted of reading a 4-minute baseline neutral script and playing an 18-minute hypnosis tape to 3 researchers involved in the BIS neurofeedback study. In addition to BIS monitoring, autonomic monitoring was performed, and this included measures of electromyography (EMG), skin temperature, skin conductance, respiratory rate, expired carbon dioxide, and heart rate variability. The resulting data were analyzed using two-tailed t tests, correlation analyses, and multivariate linear regression analyses.

RESULTS

We found that hypnosis was associated with reductions in BIS (P<.001), EMG (P<.001), respiratory rate (P<.001), skin conductance (P=.006), and very low frequency power (P=.04); it was also associated with increases in expired carbon dioxide (P<.001), skin temperature (P=.04), high frequency power (P<.001), and successive heart interbeat interval difference (P=.04) values. Decreased BIS values were associated with reduced EMG measures (R=0.76; P<.001), respiratory rate (R=0.35; P=.004), skin conductance (R=0.57; P<.001), and low frequency power (R=0.32; P=.01) and with increased high frequency power (R=-0.53; P<.001), successive heart interbeat interval difference (R=-0.32; P=.009), and heart interbeat interval SD (R=-0.26; P=.04) values.

CONCLUSIONS

Hypnosis appeared to induce mental and physical relaxation, enhance parasympathetic neural activation, and attenuate sympathetic nervous system activity, changes that were associated with BIS values. Findings from this preliminary formative evaluation suggest that the current hypnosis model may be useful for assessing autonomic physiological associations with changes in BIS values, thus motivating us to proceed with a larger investigation in trauma center nurses and physicians.

Therapeutic Potential of Vagus Nerve Stimulation for Inflammatory Bowel Diseases

The vagus nerve is a mixed nerve, comprising 80% afferent fibers and 20% efferent fibers. It allows a bidirectional communication between the central nervous system and the digestive tract. It has a dual anti-inflammatory properties via activation of the hypothalamic pituitary adrenal axis, by its afferents, but also through a vago-vagal inflammatory reflex involving an afferent (vagal) and an efferent (vagal) arm, called the cholinergic anti-inflammatory pathway. Indeed, the release of acetylcholine at the end of its efferent fibers is able to inhibit the release of tumor necrosis factor (TNF) alpha by macrophages via an interneuron of the enteric nervous system synapsing between the efferent vagal endings and the macrophages and releasing acetylcholine. The vagus nerve also synapses with the splenic sympathetic nerve to inhibit the release of TNF-alpha by splenic macrophages. It can also activate the spinal sympathetic system after central integration of its afferents. This anti-TNF-alpha effect of the vagus nerve can be used in the treatment of chronic inflammatory bowel diseases, represented by Crohn’s disease and ulcerative colitis where this cytokine plays a key role. Bioelectronic medicine, via vagus nerve stimulation, may have an interest in this non-drug therapeutic approach as an alternative to conventional anti-TNF-alpha drugs, which are not devoid of side effects feared by patients.

Comparative Study of the Impact of Active Meditation Protocol and Silence Meditation on Heart Rate Variability and Mood in Women

Aim

The aim of this study was to understand the impact of an active meditation protocol on heart rate variability (HRV) and mood in women as compared to breath-focused silence meditation.

Materials and Methods

Women experienced two different practices of 20 min each: (a) control group: silence meditation focusing on breath and (b) experiment group: active meditation that included four activities, each lasting for 5 minutes - (1) simple humming, (2) coherent heart-focused breathing with 5s of inhalation and 5s of exhalation, (3) coherent heart-focused breathing while invoking positive emotions, and (4) guided imagery about a preidentified goal. The silence meditation encouraged women to only focus on the breath. The Positive and Negative Affect Scale measured mood before/after the practice (n = 24), and emWavePro device measured HRV parameters for 5 min before/after the practices (n = 18). Statistical data analysis was done using a paired t-test.

Results

HRV (specifically, parasympathetic nervous system [PNS]) parameters showed a statistically significant improvement in the experiment group as compared to the control group. There was a statistically significant reduction in negative affect after both the practices, and the increase in positive affect was observed only for the experiment group.

Conclusions

The active meditation provides a significant enhancement in mood and HRV parameters related to PNS as compared to silence meditation where the changes in HRV were not consistent and the positive mood did not increase significantly. Future research in this area could explore the impact of such practice for a longer duration and understand the impact of each component of the meditative practices.

Hypnotic State Modulates Sensorimotor Beta Rhythms During Real Movement and Motor Imagery

Hypnosis techniques are currently used in the medical field and directly influences the patient's state of relaxation, perception of the body, and its visual imagination. There is evidence to suggest that a hypnotic state may help patients to better achieve tasks of motor imagination, which is central in the rehabilitation protocols after a stroke. However, the hypnosis techniques could also alter activity in the motor cortex. To the best of our knowledge, the impact of hypnosis on the EEG signal during a movement or an imagined movement is poorly investigated. In particular, how event-related desynchronization (ERD) and event-related synchronization (ERS) patterns would be modulated for different motor tasks may provide a better understanding of the potential benefits of hypnosis for stroke rehabilitation. To investigate this purpose, we recorded EEG signals from 23 healthy volunteers who performed real movements and motor imageries in a closed eye condition. Our results suggest that the state of hypnosis changes the sensorimotor beta rhythm during the ERD phase but maintains the ERS phase in the mu and beta frequency band, suggesting a different activation of the motor cortex in a hypnotized state.

Dissociative identity as a continuum from healthy mind to psychiatric disorders: Epistemological and neurophenomenological implications approached through hypnosis

The topic of multiple personality, redefined as Dissociative Identity Disorders (DIDs) in the DSM-5, is an intriguing and still debated disorder with a long history and deep cultural and epistemological implications, extending up to the idea of possession. Hypnosis is an appealing and valuable model to manipulate subjective experience and get an insight on both the physiology and the pathophysiology of the mind-brain functioning; it and has been closely connected with DIDs and possession since its origin in 18th century and as recently proved the capacity to yield a loss of sense of agency, mimicking delusions of alien control and spirit possession. In this study we report on five very uncommon "hypnotic virtuosos" (HVs) free from any psychiatric disorder, spontaneously undergoing the emergence of multiple identities during neutral hypnosis; this allowed us to check the relationship between their experience and fMRI data. During hypnosis the subjects underwent spontaneous non-intrusive experiences of other selves which were not recalled after the end of the session, due to post-hypnotic amnesia. The fMRI showed a significant decrease of connectivity in the Default Mode Network (DMN) especially between the posterior cingulate cortex and the medial prefrontal cortex. Our results and their contrast with the available data on fMRI in DIDs allows to draw the hypothesis of a continuum between healthy mind - where multiple identities may coexist at unconscious level and may sometimes emerge to the consciousness - and DIDs, where multiple personalities emerge as dissociated, ostensibly autonomous components yielding impaired functioning, subject's loss of control and suffering. If this is the case, it seems more reasonable to refrain from seeking for a clear-cut limit between normality (anyway a conventional, statistical concept) and pathology, and accept a grey area in between, where ostensibly odd but non-pathological experiences may occur (including so-called non-ordinary mental expressions) without calling for treatment but, rather, for being properly understood.

Soothing Your Heart and Feeling Connected: A New Experimental Paradigm to Study the Benefits of Self-Compassion

Self-compassion and its cultivation in psychological interventions are associated with improved mental health and well-being. However, the underlying processes for this are not well understood. We randomly assigned 135 participants to study the effect of two short-term self-compassion exercises on self-reported-state mood and psychophysiological responses compared to three control conditions of negative (rumination), neutral, and positive (excitement) valence. Increased self-reported-state self-compassion, affiliative affect, and decreased self-criticism were found after both self-compassion exercises and the positive-excitement condition. However, a psychophysiological response pattern of reduced arousal (reduced heart rate and skin conductance) and increased parasympathetic activation (increased heart rate variability) were unique to the self-compassion conditions. This pattern is associated with effective emotion regulation in times of adversity. As predicted, rumination triggered the opposite pattern across self-report and physiological responses. Furthermore, we found partial evidence that physiological arousal reduction and parasympathetic activation precede the experience of feeling safe and connected.

Effects of a Brief Hypnosis Relaxation Induction on Subjective Psychological States, Cardiac Vagal Activity, and Breathing Frequency

This study investigated the effects of a brief hypnosis including relaxation suggestions on physiological markers of relaxation, cardiac vagal activity, and breathing frequency. Forty participants were tested in a within-subjects design. Participants listened to a recorded hypnosis session and to a nonhypnotic recording. No differences were found regarding cardiac vagal activity. Participants breathed significantly faster during the audio conditions (hypnosis and nonhypnotic recording) in comparison to resting measures. After hypnosis, subjective arousal was significantly lower and emotional valence was significantly more positive than after the nonhypnotic recording condition. The relaxing effects of hypnosis that includes relaxation suggestions appear to be located at the subjective level but not at the peripheral physiological level.

Effects of hypnosis on the relative parasympathetic tone assessed by ANI (Analgesia/Nociception Index) in healthy volunteers: a prospective observational study

Hypnosis has shown an effect on the regulation of the autonomic nervous system by increasing parasympathetic activity. The Analgesia/Nociception Index (ANI) is derived from heart rate variability and represents the relative parasympathetic tone. We investigated the effects of hypnosis on ANI in healthy volunteers. Participants to the 2016 International Hypnosis congress, Saint Malo, France were recruited in this prospective observational study. After comfortable positioning of the subject in the sitting position (T0), the hypnotic trance was induced (T1) then conducted with suggestions of comfort (T2) before return to normal consciousness (T3). The ANI, heart rate (HR) and respiratory rate (RR) were recorded at the different time-points. Forty subjects were enrolled (31 women, 9 men). The mean ± SD ANI at T2 (84 ± 12) was significantly greater than at T0 (60 ± 10), T1 (62 ± 9) and T3 (59 ± 11). The median [25th-75th percentile] ANI values at T2 were significantly greater in women (90 [83-95]) than in men (74 [68-83]). There were no significant variations of HR during time. The median [25th-75th percentile] RR at T1 (16 [14-18] breaths/min) and T2 (14 [12-16] breaths/min) were significantly smaller than at T0 (18 [16-20] breaths/min) and T3 (18 [16-20] breaths/min). This study shows that hypnosis induces an increase in the relative parasympathetic tone assessed by ANI in healthy volunteers, with greater ANI values observed in women. These results suggest that ANI monitoring may provide an objective tool for the measurement of the intensity of the hypnotic process, although this should be confirmed by further studies.

Hypnosis in the Treatment of Major Depression: An Analysis of Heart Rate Variability

Hypnosis is an adjuvant treatment of major depression (MD). Heart rate variability (HRV) can assess the autonomic nervous system, which is associated with MD, and HRV is decreased in MD patients. There is a lack of research on HRV changes before, during, and after the use of hypnosis in MD patients. A total of 21 MD patients participated in this study, and 5-minute electrocardiograms were recorded before, during, and after hypnosis. Compared with the prehypnotic condition, HRV parameters significantly (p < .01) increased in the hypnotic and posthypnotic conditions. The results suggest that hypnosis treatment should bring some functional improvement to the autonomic nervous system. HRV is potentially a useful tool that quantifies the physiological impact of hypnosis treatment in MD patients.

Sex differences in healthy human heart rate variability: A meta-analysis

The present meta-analysis aimed to quantify current evidence on sex differences in the autonomic control of the heart, indexed by measures of heart rate variability (HRV) in healthy human subjects. An extensive search of the literature yielded 2020 titles and abstracts, of which 172 provided sufficient reporting of sex difference in HRV. Data from 63,612 participants (31,970 females) were available for analysis. Meta-analysis yielded a total of 1154 effect size estimates (k) across 50 different measures of HRV in a cumulated total of 296,247 participants. Females showed a significantly lower mean RR interval and standard deviation of RR intervals (SDNN). The power spectral density of HRV in females is characterized by significantly less total power that contains significantly greater high- (HF) and less low-frequency (LF) power. This is further reflected by a lower LF/HF ratio. Meta-regression revealed significant effects of age, respiration control and the length of recording available for analysis. Although women showed greater mean heart rate, they showed greater vagal activity indexed by HF power of HRV. Underlying mechanisms of these findings are discussed.

Alterations in electrodermal activity and cardiac parasympathetic tone during hypnosis

Exploring autonomic nervous system (ANS) changes during hypnosis is critical for understanding the nature and extent of the hypnotic phenomenon and for identifying the mechanisms underlying the effects of hypnosis in different medical conditions. To assess ANS changes during hypnosis, electrodermal activity and pulse rate variability (PRV) were measured in 121 young adults. Participants either received hypnotic induction (hypnosis condition) or listened to music (control condition), and both groups were exposed to test suggestions. Blocks of silence and experimental sound stimuli were presented at baseline, after induction, and after de-induction. Skin conductance level (SCL) and high frequency (HF) power of PRV measured at each phase were compared between groups. Hypnosis decreased SCL compared to the control condition; however, there were no group differences in HF power. Furthermore, hypnotic suggestibility did not moderate ANS changes in the hypnosis group. These findings indicate that hypnosis reduces tonic sympathetic nervous system activity, which might explain why hypnosis is effective in the treatment of disorders with strong sympathetic nervous system involvement, such as rheumatoid arthritis, hot flashes, hypertension, and chronic pain. Further studies with different control conditions are required to examine the specificity of the sympathetic effects of hypnosis.

Mechanisms of hypnosis: toward the development of a biopsychosocial model

Evidence supports the efficacy of hypnotic treatments, but there remain many unresolved questions regarding how hypnosis produces its beneficial effects. Most theoretical models focus more or less on biological, psychological, and social factors. This scoping review summarizes the empirical findings regarding the associations between specific factors in each of these domains and response to hypnosis. The findings indicate that (a) no single factor appears primary, (b) different factors may contribute more or less to outcomes in different subsets of individuals or for different conditions, and (c) comprehensive models of hypnosis that incorporate factors from all 3 domains may ultimately prove to be more useful than more restrictive models that focus on just 1 or a very few factors.