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American Journal of Clinical Hypnosis
ISSN: (Print) (Online) Journal homepage: www.tandfonline.com/journals/ujhy20
Sleepiness may predict hypnotizability, while
personality traits do not
Juliette Gelebart, Sophie Schlatter, Maxime Billot & Ursula Debarnot
To cite this article: Juliette Gelebart, Sophie Schlatter, Maxime Billot & Ursula Debarnot (20 Sep
2024): Sleepiness may predict hypnotizability, while personality traits do not, American Journal
of Clinical Hypnosis, DOI: 10.1080/00029157.2024.2387360
To link to this article: https://doi.org/10.1080/00029157.2024.2387360
Published online: 20 Sep 2024.
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Sleepiness may predict hypnotizability, while personality traits
do not
Juliette Gelebart
a
, Sophie Schlatter
b
, Maxime Billot
c
, and Ursula Debarnot
a,d
a
Universite Claude Bernard Lyon 1, Villeurbanne, France;
b
University Claude Bernard Lyon 1, Lyon, France;
c
Poitiers University Hospital, Poitiers, France;
d
Institut Universitaire de France, Paris, France
ABSTRACT
Sleepiness and personality traits have been controversially reported as
associated to individual hypnotizability level i.e. receptiveness to hyp-
notic suggestions and behave accordingly. In this study, we further
investigate the relationship between the level of general daytime
sleepiness and personality traits with the level of hypnotizability.
Seventy-eight healthy young volunteers (34 women) completed the
fast assessment of general daytime sleepiness and personality with the
Epworth Sleepiness Scale and the 10-item Big Five Inventory respec-
tively, and underwent hypnotic evaluation through the Harvard Group
Scale of Hypnotic Susceptibility Form A (HGSHS:A). Main ndings
revealed a correlation between sleepiness and hypnotizability levels,
and no inuence of personality traits. Interestingly, women exhibited
higher levels of hypnotizability compared to men. Taken together,
these results suggest that sleepiness assessment might be considered
as a predictive tool to hypnotic suggestions, which would oer prac-
tical insight for enhancing hypnosis intervention ecacy.
KEYWORDS
Gender; hypnotic
susceptibility; personality;
sleepiness
Hypnosis may be defined as a state of consciousness involving focused attention through an
intensified absorption in inner experiences, accompanied by a reduction in peripheral
awareness and elevated responsiveness to suggestions (Elkins et al., 2015). Over the past
two decades, numerous studies have contributed to significant progress in our under-
standing of the effectiveness of hypnotically mediated treatments across various clinical
conditions. Specifically, hypnosis has been reported as a valuable therapeutic tool for pain
management (Hammond, 2007; Jensen & Patterson, 2014; Tome-Pires & Miro, 2012), such
as musculoskeletal and neuropathic pain (Langlois et al., 2022), for post-traumatic stress
disorder (PTSD) symptoms (Rotaru & Rusu, 2016) and for other problems and conditions
such as depression (Alladin & Alibhai, 2007; Yapko, 2024), anxiety (Hammond, 2010), and
addiction (Lynn et al., 2010). However, the efficacy of hypnosis may be influenced by the
degree of receptiveness to hypnotic suggestions, a capacity commonly referred to as
hypnotizability (Piccione et al., 1989). This psychophysiological trait predicts the indivi-
dual’s susceptibility to enter hypnosis and to accept suggestions aimed at modifying
perception, memory and behavior (Meyer & Lynn, 2011). It can be measured by standar-
dized questionnaires, which usually consist of a hypnotic induction procedure, followed by
behavioral suggestions, such as in the Harvard Group Scale of Hypnotic Susceptibility,
CONTACT Juliette Gelebart juliette.gelebart@univ-lyon1.fr Inter-University Laboratory of Human Movement Biology
(LIBM), Universite Claude Bernard , 29 Boulevard du 11 Novembre 1918, Dubois Building, Villeurbanne 69100, France
AMERICAN JOURNAL OF CLINICAL HYPNOSIS
https://doi.org/10.1080/00029157.2024.2387360
© 2024 American Society of Clinical Hypnosis
Form A HGSHS:A (Shor & Orne, 1963) allowing to classify individuals based on their
receptiveness to hypnotic suggestions, ranging from low to high hypnotizability.
Accumulated findings have demonstrated that individuals with a high level of hypnotiz-
ability tend to exhibit enhanced cognitive and physiological processes, including for
instance greater proficiency in mental skills e.g. motor imagery quality (Ruggirello et al.,
2019), pain control (Santarcangelo & Carli, 2021), higher attentional focusing efficiency
(Cojan et al., 2015), deeper absorption (Council & Green, 2004) and even a greater prone-
ness to modulate the activity of the immune system (Gruzelier, 2002). Given the physio-
cognitive advantages linked to a high hypnotizability trait, examining the factors that make
some individuals more responsive to hypnotic suggestions than others remain a central
issue of both fundamental and clinical research in hypnosis (De Pascalis, 2024; Jensen et al.,
2017; Oakley & Halligan, 2013). From a practical standpoint, optimizing the swift identi-
fication of individual hypnotizability traits through predictive factors should offer an
effective means for determining personalized health interventions, which in turn may
contribute to enhanced therapeutic outcomes. To date, only a few studies have reported
a link between individual hypnotizability and diurnal sleepiness levels, or personality traits,
but findings remain controversial and may not directly translate to clinical practice e.g
(Evans, 1977; Zhang et al., 2017). However, they still offer valuable theoretical support for
further examine whether hypnotizability level is associated to the level of sleepiness and
personality traits.
In the seminal study into the interplay of sleep and hypnosis, Evans (1977) observed that
high hypnotizable participants fall asleep significantly more quickly compared to low
hypnotizable participants. These findings provided a support that sleep and hypnosis
might share some common mechanisms likely attributable to the capacity to change
psychological sets, attentional states, and states of awareness (Evans, 1977). Interestingly,
recent studies have hypothesized that interoceptive sensibility, which encompasses the
perception of visceral and proprioceptive signals, could be the key mechanism influencing
the relationship between hypnotizability and sleep (Cordi & Rasch, 2022; Diolaiuti et al.,
2020). Therefore, high hypnotizable individuals are more able to fall asleep easily, by an
overall detachment from the external environment with an attentional focus on the current
internal experience (i.e. absorption), which is externally induced by the hypnotist (Sodre
et al., 2023). Yet, only the study by Móró et al. (2011) tested whether general daytime
sleepiness, with the Epworth Sleepiness Scale ESS (Johns, 1991), correlated with the
hypnotizability level (Móró et al., 2011). They reported a difference in daytime sleepiness
between the lower half hypnotizable participants and the higher one, which somewhat
support the relationship between sleep and hypnosis. However, they did not find any
correlations between the self-reported daytime sleepiness and the hypnotizability levels
(r = 0.20). Yet, these findings need to be replicated to clarify and establish whether daytime
sleepiness can indeed be associated to hypnotizability level. This would enhance the validity,
consistency, and credibility of this relationship, enabling the use of these data as a quick and
easily implementable assessment tool.
To date, despite numerous attempts in hypnosis research to examine the relationships
between hypnotizability and personality traits, most of the reported findings have failed to
conclusively identify a discernible and robust link. Correlations between hypnotizability
and personality traits considered similar to those induced by the hypnotic state have been
observed. This includes among others imaginative involvement (Hilgard, 1970), vividness
2J. GELEBART ET AL.
of imagery (Farthing et al., 1983) and absorption (Piesbergen & Peter, 2006). Regarding
more general personality traits without an apparent connection to hypnosis, the results are
more ambiguous. Recent research in personality psychology has widely accepted and settled
upon the “Big Five” : a set of five major dimensions – Neuroticism, extraversion, agree-
ableness, conscientiousness, and openness to experience – forming a comprehensive sum-
mary of individual differences in personality (Costa & McCrae, 1985; Plaisant et al., 2010)
that may be assessed by the Big Five Inventory (BFI). Considering absorption as a crucial
mechanism in hypnotizability, it has been showed to be linked to the openness trait (Glisky
& Kihlstrom, 1993; Tellegen & Atkinson, 1974). Accordingly, some studies have only
reported a weak correlation between hypnotizability and openness to experience (Glisky
et al., 1991; Malinoski & Lynn, 1999; Nordenstrom & Meier, 2002). More recently, Zhang
et al. (2017) reported weak correlation between openness, extraversion, and agreeableness
traits only in individuals with high levels of hypnotizability (Zhang et al., 2017), while Green
(2004) did not find any significant association between personality and hypnotizability
(Green, 2004). Therefore, the relationship between hypnosis and personality remains
unclear and merits further investigation.
The aim of the present study was to determine whether the level of hypnotizability might
be associated to the general daytime sleepiness, and to personality traits. We aimed to
address this issue by devising an easy-to-implement assessments applicable to both clinical
practitioners and researchers in hypnosis, thereby using brief, reliable and standardized
questionnaires.
Method
Participants
Seventy-eight healthy volunteers (24.21 ± 2.98 years, 34 women) took part in the experi-
ment. Participants were students at the University Claude Bernard Lyon 1 (France) and
were recruited through public bulletin boards and e-mailing list announcements. All
participants were informed that the study was conducted to collect data about hypnotiz-
ability and that they would be able to learn about their own level of hypnotizability without
further details regarding the aim of the study. They were also informed that they would be
videotaped during the hypnotizability test to ensure the validity of the obtained scores by
checking their behavioral responses a posteriori. All participants signed an informed
consent form before the study began in accordance with Helsinki and this study was
approved by the Institutional Review Board of the University of Lyon (N° : 2023-10-
19-002).
General design
First, the day before the experiment, participants were asked to fill in individual on-line
forms of the Epworth Sleepiness Scale (ESS) to assess general daytime sleepiness propensity
(Johns, 1991), and the 10-item Big Five Inventory BFI-10 (Courtois et al., 2020). Then,
participants were invited to the laboratory for the assessment of their hypnotizability in
a group session using the Harvard Group Scale of Hypnotic Susceptibility, Form
A (HGSHS:A), conducted by a certified hypnotist (UD). During this hypnosis session, as
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 3
is conventionally done, 12 suggestions were given to quantify the hypnotizability of
participants according to their responses to these suggestions. The data were collected in
eight sessions held in a quiet experimental room in groups of 10 participants maximum who
were seated on a chair, about 1 m apart. Before the hypnotic induction phase, they were
asked to answer questions about their past experiences and beliefs concerning hypnosis, as
well as their level of alertness. Then, the hypnotist initiated the HGSHS:A with standardized
demystification of hypnosis to address misconceptions and negative beliefs, facilitating
optimal response. This was followed with induction and suggestions according to the
HGSHS:A conventional procedures. After the hypnosis session, participants scored their
behavioral response and subjective experience in the HGSHS:A booklet and were asked
again to evaluate their belief and alertness level (post-alertness). The session was videotaped
so that it could be noted a posteriori whether participants passed or failed each of the 12-
item objectively. Total length of the session was about 55 minutes.
Psychometric tests and questionnaires
Harvard group scale of hypnosis susceptibility: form A
At the beginning of the session, using the HGSHS:A, participants were asked about their
past experience with hypnosis, i.e. whether or not they had ever been hypnotized. We
further asked them their level of belief in the practice of hypnosis before and after HGSHS:A
procedure using a linear 100 mm visual analogue scales (VAS) anchored at either end with
“I strongly don’t believe in hypnosis” to “I strongly believe in hypnosis,” corresponding to 0
and 10 respectively. Participants indicated their responses by marking the line, and the
distance in millimeters from zero was used in subsequent analyses.
The HGSHS:A french version (see Anlló et al., 2017) is a widely used standardized
hypnosis scales composed of 12 items to screen the hypnotic responsiveness. Objective
behavioral responses to the 12 suggestions were scored, and the number of passed items
corresponded to the participant’s level of hypnotizability. Participants with scores ranging
from 0 to 4 points, 5 to 8 points, and 9 to 12 points are considered having a low, medium
and high level of hypnotizability respectively.
Sleepiness-related scales
The Epworth Sleepiness Scale (ESS) is the most used scales in the field of sleep to assess the
sleepiness propensity and demonstrated good reliability and validity (Gonçalves et al., 2023;
Johns, 1991). Individual has to rate the likelihood of falling asleep during daily situations
such as sitting and reading, or in a car, while stopped for a few minutes in the traffic. The
ESS includes eight situations, scored from 0 (“would never fall asleep”) to 3 (“very high
chance to doze”) points, resulting in a total score ranging from 0 to 24 points. Scores
ranging from 0 to 10 points correspond to the normal range of sleepiness in healthy adults.
Scores from 11 to 14 indicate mild sleepiness, scores from 15 to 17 indicate moderate
sleepiness, and scores from 18 to 24 indicate severe sleepiness. Cronbach’s alpha value was
0.81 in our study.
For control purposes, participant’s instantaneous alertness was assessed pre- and post-
hypnosis on a linear 100 mm visual analogue scales (VAS). The VAS was anchored at either
end with “very sleepy, great effort to stay awake, or fighting sleep” to “very alert,” corre-
sponding to 0 and 10 respectively.
4J. GELEBART ET AL.
Personality traits assessment
Participants’ personality traits were determined using the French 10-item version of the Big
Five Inventory BFI-Fr (Courtois et al., 2020). This shorter version consists of 10 items, rated
on a five-point Likert scale from 1 = “disagree strongly” to 5 = “agree strongly,” measuring
normal adult personality across the following five basic domains: neuroticism (N), extra-
version (E), openness to experience (O), agreeableness (A), and conscientiousness (C).
Cronbach’s alpha for the five factors ranged from a minimum of 0.74 (agreeableness) to
a maximum of 0.86 (neuroticism).
Statistical analyses
Quantile-to-quantile plots were used to explore the normality of data. Sleepiness scores
were submitted to a one-way Analysis of Variance (ANOVA) with the level of hypnotiz-
ability according to three groups (High, Medium and Low) as between factor. A two-way
ANOVA was applied to BFI-10 scores across the five BFI-10 personality domains (E, O, A,
C and N) in the High, Medium, and Low groups. Posthoc analyses with Bonferroni
correction for multiple comparisons were performed when significant effects or interaction
were found following ANOVAs.
Multivariable linear regression analysis was used to explore the factors associated with
hypnotizability (factors explored: gender, age, past hypnosis experience, belief in hypnosis,
sleepiness, and personality traits). The β coefficient (i.e., estimate the effect on the outcome
of each 1-unit increase in the independent variable), standard error (SE) and the adjusted
coefficients R
2
(i.e., percentage of variance explained) were computed. For explanatory
variables that were statistically significant, additional statistical analyses were performed:
one-sided Mann-Whitney test and Pearson correlation.
Finally, one-sided Wilcoxon signed-rank tests were performed to compare participants’
belief in the practice of hypnosis pre- and post-session, as well as their level of alertness.
Statistical analyses were performed with JASP® software (version 0.18.3.0). All hypotheses
were tested using a statistical significance level of 0.05.
Results
Harvard group scale of hypnosis susceptibility: form a score
The mean total score of hypnotizability using the HGSHS:A was 6.64 ± 2.96 which corre-
sponds to the data observed in 12 international HGSHS:A reference sample scores from
5.36 to 7.64 (Lichtenberg, 2008). Here, 26 participants (32.33%) scored as high, 21 partici-
pants (26.92%) as low, and the remaining 31 participants (39.74%) were medium.
A significative difference (Mann-Whitney U Test = 1060.5; p = .002) was found between
females (7.88 ± 2.66) and males (5.77 ± 2.82).
General daytime sleepiness and personality traits
The average score obtained by participants for the ESS questionnaire and the 10- BFI results
are indicated in Table 1. The ESS mean score of participants was 8.24 (±3.88) which
corresponds to the normative values of sleepiness in healthy adults. The results on the
five 10-BFI personality domains followed the range of a normative study carried out
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 5
internationally Openness : 2.9 ± 1.3, Consciousness : 4.0 ± 1.0, Extraversion : 3.0 ± 1.5,
Agreeableness 3.9 ± 1.1, and Neuroticism : 2.4 ± 1.4 (Mastracusa et al., 20232023).
Predictive factors of hypnotizability
ANOVA performed on the general daytime sleepiness scores across the three groups – High,
Medium, and Low levels of hypnotizability – revealed a main effect of the level of hypnotiz-
ability (F
(2,71)
= 5.57; p = .006), with higher sleepiness scores in participants having a high level
of hypnotizability compared to those with a low level (posthoc t-test t
(71)
= 3.26; p = .005). No
significant difference was observed between the Medium group and the two others (Figure 1).
In contrast, the two-way ANOVA performed on BFI-10 scores did not show a main
effect of group of level of hypnotizability (F
(2,335)
= 1.006; p = .37), and no interaction
(F
(8,335)
= 1.07; p = .38). It showed a main effect of personality domains (E, O, C, A and N;
F
(4,335)
= 7.7, p < .001).
In addition, the main result from the multivariable regression model showed that the
level of hypnotizability was strongly associated with general daytime sleepiness score (ESS;
p = .006) and the gender (p = .03). Personality traits were not associated to the level of
hypnotizability (Table 2).
Table 1. Sleepiness and personality traits scores extracted from the
ESS and 10-BIF questionnaires ranging from 0 to 24 points and 0 to
5 points respectively. Data are presented as mean (± standard
deviation).
Sleepiness (ESS) 8.24 (±3.88)
Personality traits (10-BFI) Openness 2.89 (±0.93)
Consciousness 3.54 (±0.82)
Extraversion 2.74 (±1.06)
Agreeableness 2.99 (±0.97)
Neuroticism 2.69 (±1.24)
Figure 1. Sleepiness scores from ESS questionnaire according to low (n = 21), medium (n = 31) and high
(n = 26) level of hypnotizability in participants. **p < .01.
6J. GELEBART ET AL.
As previously shown by the one-sided Mann-Whitney test on the gender factor in the
first paragraph of the results, females had a significantly higher level of hypnotizability than
males (7.88 ± 2.66 versus 5.77 ± 2.82, W = 1060.5, p = .002). Pearson correlation analysis
between the level of hypnotizability and sleepiness score further revealed a positive correla-
tion (r = 0.44, p < .001). Figure 2 depicts the relationship between hypnotizability and
sleepiness.
Complementary assessments: belief and alertness
Out of the 78 participants, 60.26% (n = 47) have never been hypnotized. In addition,
participants’ belief in the practice of hypnosis increased from 6.90 (±2.47) pre-session to
7.36 (±1.74) post-session on the VAS (one-sided Wilcoxon signed-rank test = 245,
Table 2. Multivariable regression model to identify the association between hypnotizability and six
factors: gender, age, past hypnosis experience, belief in hypnosis, sleepiness, and personality traits.
Significant relationships of the model analyses are in bold. *p < .05; **p < .01; SE is the standard error.
P-value of the model: <.001. Adjusted R
2
was 0.56.
β SE Standardized β Standardized SE p-value
Gender (Male) −2.48 1.07 −2.48 1.07 .03*
Age 0.22 0.16 0.72 0.54 .20
Previously hypnotized (Yes) 1.36 0.94 1.36 0.94 .14
Pre-hypnosis belief (VAS) −0.03 0.17 −0.07 0.42 .87
Sleepiness (ESS) 0.33 0.11 1.36 0.45 .006**
Openness −0.39 0.43 −0.35 0.38 .36
Consciousness −0.52 0.45 −0.44 0.38 .26
Extraversion −0.42 0.39 −0.44 0.41 .30
Agreeableness 0.23 0.46 0.21 0.42 .62
Neuroticism 0.12 0.35 0.14 0.42 .74
Figure 2. Pearson correlation between participants’ level of hypnotizability and sleepiness scores from
ESS questionnaire. The dashed lines indicate the 95% confidence interval. r = 0.44.
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 7
z = −2.02, p = .02). The repeated measures ANOVA taking into account the “previously
hypnotized” factor, and the pre- and post- belief in hypnosis factor, revealed an
interaction effect (F
(1,71) =
4.48, p = .04). Thereby, the difference in pre- and post-belief
levels was only observed for participants who have never been hypnotized before (Posthoc
t-test t
(71)
= −2.89, p = .04).
The level of alertness, assessed on a VAS as a control measure, revealed a significant
decrease from pre- (6.19 ± 1.82) to post-session (5.35 ± 2.29) (One-sided Wilcoxon signed-
rank test = 1351.5, z = 2.629, p = .004), consistent with typical findings in similar conditions
documented in the literature [18].
Discussion
We conducted the present study to examine whether general daytime sleepiness and
personality traits were associated to receptiveness to hypnotic suggestions. The main
finding revealed an association between the level of sleepiness and hypnotizability, but no
influence of the personality traits. Interestingly, our data further showed that women exhibit
higher levels of hypnotizability compared to men. Finally, preexisting beliefs in hypnosis
increased after the session using HGSHS:A in inexperienced individuals, without influence
on their level of hypnotizability.
The main important finding is that our results not only replicate the previously
reported difference in self-reported daytime sleepiness (ESS) between high and low
hypnotizable individuals by Móró et al. (2011), but further reinforce these observations
by demonstrating a correlation between daytime sleepiness and the level of hypnotiz-
ability (HGSHS: A). This is consistent with the existing literature suggesting that high
hypnotizable individuals, relative to the low, more easily transition from wakefulness to
daytime sleep (Evans, 1977; Móró et al., 2011). Importantly, our data showed
a correlation between general daytime sleepiness scores and the level of hypnotizability
(r = 0.44). In contrast, Móró et al. (2011) reported a weaker correlation between daytime
sleepiness scores and hypnotizability (20%), which was nearly significant (p = .06). One
possible explanation for this discrepancy may relate to the difference in the nature of the
HGSHS:A administration between the two studies (i.e., audiotape vs. live-hypnotist
here). Költő and Polito (2017) did not find differences in hypnotizability scores between
different types of HGSHS:A administration, the absence of reproducibility tests in both
their study and that of Móró et al. (2011) raises concerns regarding the reliability of
audiotape HGSHS:A compared to live human administration. The HGSHS:A screening
procedure administered live by a hypnotist may be time-consuming compared to the
audiotape method, but it provides the advantage of adapting to the pace of behavioral
responses to hypnotic suggestions, especially in group settings, such as slowing down the
script rhythm, incorporating longer periods of silence, or adding ratification/positive
feedback. Moreover, our finding from a live hypnotist administering the HGSHS:A
better aligns with the personalized and tailored approach characteristic of actual hyp-
nosis practice (Geagea et al., 2023). Thus, our data highlights the potential to use of
indirect and brief inquiries about sleepiness (e.g. derived from the ESS) in hypnosis
context of application for both patients and participants, serving as a robust predictor of
their responsiveness to hypnotic suggestions.
8J. GELEBART ET AL.
The second result of the study did not reveal any association between the personality
traits and the hypnotizability level. This finding is corroborated by a prior study conducted
by Nordenstrom and Meier (2002) where the 45-item BFI and the HGSHS:A were used,
revealing no significant relationships between personality traits and hypnotic suggestibility.
Therefore, our data further support that assessing personality traits by means of the brief
10-item BFI may not be associated with the degree of hypnotizability. Yet, several studies
using various measurements of personality traits and methods for assessing hypnotizability
have also failed to establish reliable relationships between both (Malinoski & Lynn, 1999;
Radtke & Stam, 1991). At best, weak associations between hypnotizability and openness to
experience have been emphasized by Glisky et al. (1991) albeit limited to high hypnotizable
subjects. Given that other authors have reported associations between hypnotic suscept-
ibility and extraversion-agreeableness traits, but not with openness (Malinoski & Lynn,
1999; Green, 2004), one may conclude that the assessment of personality traits does not
appear to be a stable or a reliable predictor of hypnotizability levels. However, historical
studies focusing on personality as a whole have reported that three distinct personality styles
correlated with low, medium and high hypnotizability, which have been described as
Apollonian, Odyssean and Dionysian, respectively (Greenleaf, 2006; Spiegel & Spiegel,
1978). These personality styles were defined according to various criteria reflecting the
complexity of the human personality, such as propensity to be rational, intuitive, or
antisocial, for example. Therefore, rather than focusing on just one of the five personality
domains, future studies could investigate the correlation of the combination of several
domains with hypnotizability levels.
Analysis of gender factor revealed that women (7.77 ± 3.09) had a higher level of
hypnotizability relative to men (5.23 ± 3.00). This finding is similar to those obtained in
several recent standardized studies in the domain of hypnosis using the HGSHS:A (Cardeña
et al., 2007; Költő & Polito, 2017; Page & Green, 2007), and others using different tools for
hypnotic suggestibility measurements (Asensio et al., 2018). Our data particularly replicated
those by Költő and Polito (2017) with HGSHS:A group setting where women also demon-
strated higher hypnotizability than men, particularly at a young age (mean 24.55 years vs 25
here). They further reported that women were more hypnotizable than men in a group
setting but not in an individual context and suggested that this may be due to cooperation-
type which is influenced by gender and setting. According to Charness and Rustichini
(2011) when being observed by their peers, men cooperated substantially less often, whereas
women cooperated substantially more often.
Finally, our data showed that the level of belief in hypnosis practice did not influence the
level of hypnotizability. This result is partially in line with the findings of Groth‐Marnat and
Mitchell (1998) and Shimizu (2014), suggesting that the measurement of acceptance or
resistance to hypnotic suggestions using the Therapeutic Reactance Scale (Dowd et al.,
1991) in conjunction with the use of HGSHS:A may not consistently predict differential
hypnotic responsiveness. However, it is noteworthy that Robin et al. (2005) reported
contrasting results despite using similar materials. Here, it is important to acknowledge
that our question regarding belief in hypnosis practice could have been interpreted (at least)
in two ways: either as belief in the effectiveness of therapeutic hypnosis involving beliefs
about hypnotic states, or as expectations about what would happen to the subject during the
subsequent hypnosis session using HGSHS:A. Moreover, pre-hypnotic information and
instructions from the HGSHS:A to counteract misconceptions about hypnosis and negative
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 9
beliefs and attitudes that may impede optimal responding were communicated to subjects
after asking their belief about hypnosis practice. Therefore, even if it is possible that the level
of hypnotizability may not depend on the belief in its effectiveness as a peculiar state of
consciousness, this result should be taken with caution as it may have been influenced by
the pre-hypnotic HGSHS:A information. From a practical perspective, this also emphasizes
the importance for therapists to address clients ‘misconceptions, particularly fears related to
the belief that hypnosis abilities are unnatural, such as those associated with arousing
extraordinary ability.
Summary and conclusions
To conclude, the present findings strongly support that general daytime sleepiness is
strongly associated with hypnotizability levels, while personality traits may not. Given the
study’s dedication to identify predictive factors of hypnotizability allowing a quick and easy-
to-implement assessment tools for practitioners in both clinical and research contexts, we
can recommend the use of indirect questions regarding general daytime sleepiness.
Additionally, it was shown that women exhibit higher levels of hypnotizability compared
to men. Thus, if patients or potential participants in hypnotic experiments report
a tendency to easily fall asleep in daytime situations and are women, it may enhance the
likelihood of hypnotic responsiveness.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
The work was supported by the Institut Universitaire de France [IUFDEB2020].
References
Alladin, A., & Alibhai, A. (2007). Cognitive hypnotherapy for depression: An empirical investigation.
The International Journal of Clinical and Experimental Hypnosis, 55(2), 147–166. https://doi.org/
10.1080/00207140601177897
Anlló, H., Becchio, J., & Sackur, J. (2017). French norms for the Harvard group scale of hypnotic
susceptibility, form A. HAL (Le Centre Pour La Communication Scientifique Directe), 65(2),
241–255. https://doi.org/10.1080/00207144.2017.1276369
Asensio, X. P., Escolano, A. F., & Rodríguez, J. R. (2018). Psychometric analysis of the barber
suggestibility scale in a clinical population. The American Journal of Clinical Hypnosis, 60(4),
386–402. https://doi.org/10.1080/00029157.2017.1421138
Cardeña, E., Kallio, S., Terhune, D. B., Buratti, S., & Lööf, A. (2007). The effects of translation and sex
on hypnotizability testing. Contemporary Hypnosis, 24(4), 154–160. https://doi.org/10.1002/ch.340
Charness, G., & Rustichini, A. (2011). Gender differences in cooperation with group membership.
Games and Economic Behavior, 72(1), 77–85. https://doi.org/10.1016/j.geb.2010.07.006
Cojan, Y., Piguet, C., & Vuilleumier, P. (2015). What makes your brain suggestible? Hypnotizability is
associated with differential brain activity during attention outside hypnosis. Neuroimage: Reports,
117, 367–374. https://doi.org/10.1016/j.neuroimage.2015.05.076
10 J. GELEBART ET AL.
Cordi, M. J., & Rasch, B. (2022). Hypnotizability may relate to interoceptive ability to accurately
perceive sleep depth: An exploratory study. The International Journal of Clinical and Experimental
Hypnosis, 70(4), 385–402. https://doi.org/10.1080/00207144.2022.2130068
Costa, P. T., Jr., & McCrae, R. R. (1985). Concurrent validation after 20 years: Implications of
personality stability for its assessment. In J. N. Butcher & C. D. Spielberger (Eds.), Advances in
personality assessment (Vol. 4, pp. 31–54). Erlbaum.
Council, J. R., & Green, J. P. (2004). Examining the absorption-hypnotizability link: The roles of
acquiescence and consistency motivation. The International Journal of Clinical and Experimental
Hypnosis, 52(4), 364–377. https://doi.org/10.1080/00207140490883950
Courtois, R., Petot, J., Plaisant, O., Allibe, B., Lignier, B., Réveillère, C., Lecocq, G., & John, O. P.
(2020). Validation française du Big Five Inventory à 10 items (BFI-10). L’Encéphale, 46(6),
455–462. https://doi.org/10.1016/j.encep.2020.02.006
De Pascalis, V. (2024). Brain functional correlates of resting hypnosis and hypnotizability: A review.
Brain Sciences, 14(2), 115. https://doi.org/10.3390/brainsci14020115
Diolaiuti, F., Fantozzi, M. P. T., DiGalante, M., D’Ascanio, P., Faraguna, U., Sebastiani, L., &
Santarcangelo, E. L. (2020). Association of hypnotizability and deep sleep: Any role for interocep-
tive sensibility? Experimental Brain Research, 238(9), 1937–1943. https://doi.org/10.1007/s00221-
020-05853-4
Dowd, E. T., Milne, C. R., & Wise, S. L. (1991). The therapeutic reactance scale: A measure of
psychological reactance. Journal of Counseling & Development, 69(6), 541–545. https://doi.org/10.
1002/j.1556-6676.1991.tb02638.x
Elkins, G., Barabasz, A., Council, J. R., & Spiegel, D. (2015). Advancing research and practice: The
revised APA division 30 definition of hypnosis. The American Journal of Clinical Hypnosis, 57(4),
378–385. https://doi.org/10.1080/00029157.2015.1011465
Evans, F. J. (1977). Hypnosis and sleep: The control of altered states of awareness*. Annals of the
New York Academy of Sciences, 296(1), 162–174. https://doi.org/10.1111/j.1749-6632.1977.
tb38170.x
Farthing, C. W., Venturino, M., & Brown, S. W. (1983). Relationship between two different types of
imagery vividness questionnaire items and three hypnotic susceptibility scale factors: A brief
communication. The International Journal of Clinical and Experimental Hypnosis, 31(1), 8–13.
https://doi.org/10.1080/00207148308407176
Geagea, D., Ogez, D., Kimble, R., & Tyack, Z. (2023). Redefining hypnosis: A narrative review of
theories to move towards an integrative model. Complementary Therapies in Clinical Practice, 54,
101826. https://doi.org/10.1016/j.ctcp.2023.101826
Glisky, M. L., & Kihlstrom, J. F. (1993). Hypnotizability and facets of openness. The International
Journal of Clinical and Experimental Hypnosis, 41(2), 112–123. https://doi.org/10.1080/
00207149308414542
Glisky, M. L., Tataryn, D. J., Tobias, B. A., Kihlstrom, J. F., & McConkey, K. M. (1991). Absorption,
openness to experience, and hypnotizability. Journal of Personality & Social Psychology, 60(2),
263–272. https://doi.org/10.1037/0022-3514.60.2.263
Gonçalves, M. T., Malafaia, S., Santos, J. M. D., Roth, T., & Marques, D. R. (2023). Epworth sleepiness
scale: A meta-analytic study on the internal consistency. Sleep Medicine, 109, 261–269. https://doi.
org/10.1016/j.sleep.2023.07.008
Green, J. P. (2004). The five factor model of personality and hypnotizability: Little variance in
common. Contemporary Hypnosis, 21(4), 161–168. https://doi.org/10.1002/ch.303
Greenleaf, M. (2006). Mind styles and the hypnotic induction profile: Measure and match to enhance
medical treatment. The American Journal of Clinical Hypnosis, 49(1), 41–58. https://doi.org/10.
1080/00029157.2006.10401551
Groth‐Marnat, G., & Mitchell, K. (1998). Responsiveness to direct versus indirect hypnotic proce-
dures: The role of resistance as a predictor variable. The International Journal of Clinical and
Experimental Hypnosis, 46(4), 324–333. https://doi.org/10.1080/00207149808410012
Gruzelier, J. H. (2002). A review of the impact of hypnosis, relaxation, guided imagery and individual
differences on aspects of immunity and health. Stress, 5(2), 147–163. https://doi.org/10.1080/
10253890290027877
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 11
Hammond, D. C. (2007). Review of the efficacy of clinical hypnosis with headaches and migraines.
The International Journal of Clinical and Experimental Hypnosis, 55(2), 207–219. https://doi.org/
10.1080/00207140601177921
Hammond, D. C. (2010). Hypnosis in the treatment of anxiety- and stress-related disorders. Expert
Review of Neurotherapeutics, 10(2), 263–273. https://doi.org/10.1586/ern.09.140
Hilgard, J. R. (1970). Personality and hypnosis. A study of imaginative involvement. University of
Chicago Press.
Jensen, M. P., Jamieson, G. A., Lutz, A., Mazzoni, G., McGeown, W. J., Santarcangelo, E. L.,
Demertzi, A., De Pascalis, V., Bányai, É. I., Rominger, C., Vuilleumier, P., Faymonville, M. E., &
Terhune, D. B. (2017). New directions in hypnosis research: Strategies for advancing the cognitive
and clinical neuroscience of hypnosis. Neuroscience of Consciousness, 3(1), nix004. https://doi.org/
10.1093/nc/nix004
Jensen, M. P., & Patterson, D. R. (2014). Hypnotic approaches for chronic pain management: Clinical
implications of recent research findings. The American Psychologist, 69(2), 167–177. https://doi.
org/10.1037/a0035644
Johns, M. W. (1991). A new method for measuring daytime sleepiness: The Epworth sleepiness scale.
SLEEP, 14(6), 540–545. https://doi.org/10.1093/sleep/14.6.540
Költő, A., & Polito, V. (2017). Changes in the sense of agency during hypnosis: The Hungarian
version of the sense of agency rating scale (SOARS-HU) and its relationship with phenomenolo-
gical aspects of consciousness. Consciousness and Cognition, 49, 245–254. https://doi.org/10.1016/j.
concog.2017.02.009
Langlois, P., Perrochon, A., Ragazzoni, D., Rainville, P., Wood, C., Vanhaudenhuyse, A., Pageaux, B.,
Ounajim, A., Lavallière, M., Debarnot, U., Luque-Moreno, C., Roulaud, M., Simoneau, M.,
Goudman, L., Moens, M., Rigoard, P., & Billot, M. (2022). Hypnosis to manage musculoskeletal
and neuropathic chronic pain: A systematic review and meta-analysis. Neuroscience &
Biobehavioral Reviews, 135, 104591. https://doi.org/10.1016/j.neubiorev.2022.104591
Lichtenberg, P. (2008). Israeli norms for the Harvard group scale of hypnotic susceptibility, form A.
The International Journal of Clinical and Experimental Hypnosis, 56(4), 384–393. https://doi.org/
10.1080/00207140802255385
Lynn, S. J., Green, J. P., Accardi, M., & Cleere, C. (2010). Hypnosis and smoking cessation: The state
of the science. The American Journal of Clinical Hypnosis, 52(3), 177–181. https://doi.org/10.1080/
00029157.2010.10401717
Malinoski, P., & Lynn, S. J. (1999). The plasticity of early memory reports: Social pressure, hypnotiz-
ability, compliance and interrogative suggestibility. The International Journal of Clinical and
Experimental Hypnosis, 47(4), 320–345. https://doi.org/10.1080/00207149908410040
Mastrascusa, R. C., De Oliveira Fenili Antunes, M. L., De Albuquerque, N. S., Virissimo, S. L.,
Moura, M. F., Motta, B. V. M., De Lara Machado, W., Moret-Tatay, C., & Irigaray, T. Q. (2023).
Evaluating the complete (44-item), short (20-item) and ultra-short (10-item) versions of the Big
Five Inventory (BFI) in the Brazilian population. Scientific Reports, 13(1). https://doi.org/10.1038/
s41598-023-34504-1
Meyer, E. C., & Lynn, S. J. (2011). Responding to hypnotic and nonhypnotic suggestions:
Performance standards, imaginative suggestibility, and response expectancies. The International
Journal of Clinical and Experimental Hypnosis, 59(3), 327–349. https://doi.org/10.1080/00207144.
2011.570660
Móró, L., Noreika, V., Revonsuo, A., & Kallio, S. (2011). Hypnotizability, sleepiness, and subjective
experience. The International Journal of Clinical and Experimental Hypnosis, 59(2), 211–224.
https://doi.org/10.1080/00207144.2011.546220
Nordenstrom, B. K., & Meier, B. P. (2002). The “Big Five” and hypnotic suggestibility. The
International Journal of Clinical and Experimental Hypnosis, 50(3), 276–281. https://doi.org/10.
1080/00207140208410103
Oakley, D. A., & Halligan, P. W. (2013). Hypnotic suggestion: Opportunities for cognitive
neuroscience. Nature Reviews. Neuroscience, 14(8), 565–576. https://doi.org/10.1038/nrn3538
12 J. GELEBART ET AL.
Page, R. A., & Green, J. P. (2007). An update on age, hypnotic suggestibility, and gender: A brief
report. The American Journal of Clinical Hypnosis, 49(4), 283–287. https://doi.org/10.1080/
00029157.2007.10524505
Piccione, C., Hilgard, E. R., & Zimbardo, P. G. (1989). On the degree of stability of measured
hypnotizability over a 25-year period. Journal of Personality & Social Psychology, 56(2), 289–295.
https://doi.org/10.1037/0022-3514.56.2.289
Piesbergen, C., & Peter, B. (2006). An investigation of the factor structure of the Harvard Group Scale
of Hypnotic Susceptibility, Form A (HGSHS: A). Contemporary Hypnosis, 23(2), 59–71. https://
doi.org/10.1002/ch.311
Plaisant, O., Courtois, R., Réveillère, C., Mendelsohn, G. A., & John, O. P. (2010). Validation par
analyse factorielle du Big Five Inventory français (BFI-Fr). Analyse convergente avec le NEO-PI-R.
Annales Médico-psychologiques, revue psychiatrique, 168(2), 97–106. https://doi.org/10.1016/j.amp.
2009.09.003
Radtke, H. L., & Stam, H. J. (1991). The relationship between absorption, openness to experience,
anhedonia, and susceptibility. The International Journal of Clinical and Experimental Hypnosis, 39
(1), 39–56. https://doi.org/10.1080/00207149108409617
Robin, B. R., Kumar, V. K., & Pekala, R. J. (2005). Direct and indirect scales of hypnotic susceptibility:
Resistance to therapy and psychometric comparability abstract. The International Journal of
Clinical and Experimental Hypnosis, 53(2), 135–147. https://doi.org/10.1080/00207140590927617
Rotaru, T. S., & Rusu, A. (2016). A meta-analysis for the efficacy of hypnotherapy in alleviating PTSD
symptoms. The International Journal of Clinical and Experimental Hypnosis, 64(1), 116–136.
https://doi.org/10.1080/00207144.2015.1099406
Ruggirello, S., Campioni, L., Piermanni, S., Sebastiani, L., & Santarcangelo, E. L. (2019). Does
hypnotic assessment predict the functional equivalence between motor imagery and action?
Brain & Cognition, 136, 103598. https://doi.org/10.1016/j.bandc.2019.103598
Santarcangelo, E. L., & Carli, G. (2021). Individual traits and pain treatment: The case of
hypnotizability. Frontiers in Neuroscience, 15, 15. https://doi.org/10.3389/fnins.2021.683045
Shimizu, T. (2014). A causal model explaining the relationships governing beliefs, attitudes, and
hypnotic responsiveness. The International Journal of Clinical and Experimental Hypnosis, 62(2),
231–250. https://doi.org/10.1080/00207144.2014.869142
Shor, R. E., & Orne, E. C. (1963). Norms on the Harvard group scale of hypnotic susceptibility, form
A. The International Journal of Clinical and Experimental Hypnosis, 11(1), 39–47. https://doi.org/
10.1080/00207146308409226
Sodre, M. E. J., Wießner, I., Irfan, M., Schenck, C. H., & Mota-Rolim, S. A. (2023). Awake or sleeping?
Maybe both . . . A review of sleep-related dissociative states. Journal of Clinical Medicine, 12(12),
3876. https://doi.org/10.3390/jcm12123876
Spiegel, H., & Spiegel, D. (1978). Trance and treatment: Clinical uses of hypnosis. Basic Books
(Reprinted, Washington, DC, American Psychiatric Press, 1987).
Tellegen, A., & Atkinson, G. (1974). Openness to absorbing and self-altering experiences (“absorp-
tion”), a trait related to hypnotic susceptibility. Journal of Abnormal Psychology, 83(3), 268–277.
https://doi.org/10.1037/h0036681
Tome-Pires, C., & Miro, J. (2012). Hypnosis for the management of chronic and cancer
procedure-related pain in children. The International Journal of Clinical and Experimental
Hypnosis, 60(4), 432–457. https://doi.org/10.1080/00207144.2012.701092
Yapko, M. D. (2024). Guest editorial: Hypnosis in treating depression: The despair of young people.
The American Journal of Clinical Hypnosis, 66(2), 93–96. https://doi.org/10.1080/00029157.2024.
2343622
Zhang, Y., Wang, Y., Shen, C., Ye, Y., Shen, S., Zhang, B., Wang, J., Chen, W., & Wang, W. (2017).
Relationship between hypnosis and personality trait in participants with high or low hypnotic
susceptibility. Neuropsychiatric Disease and Treatment, 13, 1007–1012. https://doi.org/10.2147/
ndt.s134930
AMERICAN JOURNAL OF CLINICAL HYPNOSIS 13
