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Copyright ? 2006-2013 Scientific Research Publishing Inc. All rights reserved.
2011. Vol.2, No.4, 371-375
Copyright © 2011 SciRes. DOI:10.4236/psych.2011.24058
An Investigation into Personality, Stress and Sleep with Reports of
Hallucinations in a Normal Population
—Hallucinations in Normal Population
Jim Barnes1, Lucy Koch1, Chloe Wilford1, Laura Boubert2
1Department of Psychology, Oxford Brookes University, Oxford, United Kingdom;
2Department of Psychology, University of Westminster, London, United Kingdom.
Received March 28th, 2011; revised May 6th, 2011; accepted June 13th, 2011.
Emotion, especially anxiety, has been implicated in triggering hallucinations. Sleep behaviour has also been re-
ported to have a modest influence on the judgments that lead to hallucinatory experiences. We report an investi-
gation on the prediction of hallucinatory predisposition which explored emotion and associated processes (stress,
personality and sleep behaviour) using a questionnaire survey in a student population (N = 127). Findings indi-
cated significant associations between perceived stress levels and sleep, with stress and being a significant pre-
dictor of the hallucinatory experience. In addition there was a predictive relationship between the proneness to
hallucinate and schizotypal personality traits, characterised by the subscale of cognitive disorganisation and un-
usual experiences. Stress and anxiety together with personality may need to be considered in the understanding
of hallucinatory experience.
Keywords: Hallucinations, Normal Population, Personality
Hallucinations are perceptions in the absence of an external
stimulus (Bentall, 1990). The phenomena can occur in any
sensory modality and can arise through neurologic disease,
psychopathology, and the use of recreational drugs. Indeed
hallucinations are widely accepted to be symptomatic of a psy-
chotic disorder and like schizophrenia they occur within a
clinical setting, however recently they have been investigated in
healthy people who have a predisposition for visual hallucina-
tions (Johns, 2005; Johns & Os van, 2001). Though not psy-
chotic, these people can still have hallucinations as seen in
clinical populations. Along these lines, studies evaluating the
prevalence of hallucinations in the general public continually
observe, on average, that 35% - 40% of individuals admit that
they have had some experience of visual hallucinatory phe-
nomenon (Barrett & Etheridge, 1992; Ohayon, 2000; Posey &
Losch, 1983; Tien, 1991). Higher degrees of negative affect,
particularly depression, anxiety, and stress, have been repeat-
edly and consistently reported to correlate with hallucinations
(Delespaul, Vries de, & Os van, 2002; Freeman & Garety,
2003). Observations like these suggest that emotional distress
might have a direct influence on the onset of hallucinations or
that some of the mechanisms that cause hallucinations may be
managed or moderated by affective arousal (Slade & Bentall,
Studies have also focused on the relationship of personality
traits and hallucinatory experiences using non-clinical samples.
The Launay-Slade Hallucination Scale (Launay & Slade, 1981),
a scale that is used to measure tendency to visually hallucinate,
correlates with scores on neuroticism and openness to experi-
ence features on the NEO Personality Inventory (Costa &
McCrae, 1992), which suggests that certain personality traits
have an impact on the occurrence of hallucinations (Laroi &
Van der Linden, 2005). In fact, a certain personality trait that
reportedly influences the occurrence of hallucinations in
healthy people is schizotypy (Claridge, Clark, & Davis, 1997).
Schizotypy is explained as being a psychological idea that
demonstrates a constant sequence of personality traits and en-
counters that are connected with psychosis and, specifically,
schizophrenia (Claridge, 1997). Schizotypy is different from
schizophrenia, as increased levels of schizotypy do not mean
that a person is in poor health (Claridge & Beech, 1995), and
certain traits are considered to be advantageous as they pertain
to creativity and academic accomplishment (Nettle, 2006).
Not unlike hallucinations, schizotypy is seen as a part of the
personality that has a normal distribution in the general popula-
tion (Claridge & Beech, 1995). The personality characteristics
that define schizotypy can be measured using the Oxford-Liv-
erpool Inventory of Feelings and Experiences (Mason, Claridge,
& Jackson, 1995) and are often broken up into four features:
unusual experiences, cognitive disorganisation, introverted
anhedonia and impulsive non-conformity (Bentall, Claridge, &
Slade, 1989; Claridge et al., 1996). Unusual experiences refers
to perceptual, hallucinatory and magical thinking; cognitive
disorganisation refers to problems with attention, concentration
and decision making; introvertive anhedonia refers to a lack of
enjoyment from social activities as well as a dislike of physical
and emotional intimacy and impulsive non-conformity refers to
violent, reckless and self-abusive behaviours.
Individuals scoring highly on measures of schizotypy are
also prone to “micro-sleeps”. “Micro-sleeps” are the result of
hyper-arousal coupled with extreme stress and involve intru-
sions of stage one sleep into waking consciousness (Oswald,
J. BARNES ET AL.
1962). Stage one sleep is the transition between wakefulness
and sleep and can be accompanied with sensory experiences
such as vivid hallucinations (Ohayon, Priest, Caulet, & Guil-
leminault, 1996). This suggests that individuals with high levels
of schizotypy personality characteristics may have a predisposi-
tion to hallucinate in times of extreme stress. Stressful events
have been shown to activate the predisposition to hallucinate in
vulnerable individuals (Nuechterlein & Dawson, 1984) and
individuals predisposed to hallucinate report higher levels of
depression, anxiety and stress, (Paulik, Bafcock, & Maybery,
2006). Also, there have been several studies that have con-
cluded that poor sleep quality is frequently connected to a cha-
otic and high stress lifestyle and, most especially, has an impact
on women living in western cultures (Rajaratnam & Arendt,
2001; Soares, 2005). The results of polysomnography studies
support this finding and suggest that generalized anxiety and
worry in otherwise healthy people can cause significant sleep
problems (Fuller, Waters, Binks, & Anderson, 1997). Along the
same line, adolescents who are chronic poor sleepers show
more noticeable behaviours and feelings of stress than good
sleepers (Kirmil-Gray, Eagleston, Gibson, & Thoresen, 1984).
This is most notable in a student population who are susceptible
to a great number of stressors (Medeiros, Mendes, Lima, &
In conclusion, research on the occurrence of hallucinatory
experiences has established that they are not only occurring in
the general population but also have many associative factors
which contribute to a person’s proneness to hallucinate. This
study investigated the link between these associations particu-
larly the possible relationship between the occurrence of hallu-
cinatory experiences and schizotypy personality characteristics,
sleep quality and stress in a student population. It is hypothe-
sised that stress and sleep quality will predict hallucinatory
predisposition and that high levels of schizotypy may increase
the likelihood of the hallucinatory experience.
The study was passed by the local university ethics commit-
tee. Participant recruitment was done via email to university
students at Oxford Brookes University, Oxford, informing them
of the study. Participants recruited were 117 students (75 fe-
male, 42 males) who were tested over a period of five weeks.
Their mean age was 22.3 years (SD = 5.3)
Participants provided basic demographic information (age,
gender) and completed the following questionnaires. All ques-
tionnaires are well known in the literature and have strong reli-
ability and validity for the both hallucinatory and sleep research
(Barnes et al., 2010).
The Undergraduate Stress Questionnaire (Crandall,
Preisler, & Aussprung, 1992)
Life stress was measured with the Undergraduate Stress
Questionnaire (USQ) (Crandall, Preisler, & Aussprung, 1992).
The USQ is an 83-item checklist designed to measure stress
among university students based on life-events life events they
have experienced in the semester. Each check mark is tallied
for a total score on the USQ. The checklist includes events such
as “death of a family member” and “lack of money”. The USQ
has been found to correlate positively with physical symptoms
and negatively with mood (Crandall et al., 1992)
Revised Hallucination Scale (RHS)
This is a 24-item questionnaire based upon the revised Lau-
nay-Slade Hallucination Scale (Launay & Slade, 1981; Morri-
son, Wells, & Nothard, 2000). It incorporates additional items
measuring predisposition to visual hallucination, predisposition
to auditory hallucinations, vividness of imagery and daydream-
ing in order to examine distinctions between these phenomena
in greater detail. It retained the revised method of scoring, al-
lowing items to be endorsed using a 4-point scale to measure
frequency (1 = never, 2 = sometimes, 3 = often, 4 = almost
always) rather than a forced true/false response.
The Pittsburgh Sleep Quality Index (PSQI) (Buysse e t al.
Sleep quality during the previous month and to discriminate
between good and poor sleepers the (PSQI) was administered.
Sleep quality is a complex phenomenon that involves several
dimensions, each of which is covered by the PSQI. The covered
domains include Subjective Sleep Quality, Sleep Latency,
Sleep Duration, Habitual Sleep Efficiency, Sleep Disturbances,
Use of Sleep Medications, and Daytime Dysfunction (Buysse,
Reynolds, Monk, Berman, & Kupfer, 1989).
The Oxford-Liverpool Inventory of Feelings and
Experiences (O-LIFE; Mason et al., 1995)
Previous research has shown that O-LIFE has high internal
consistency (Mason et al., 1995) and high test-retest reliability
(Burch, Steel, & Hemsley, 1998). So in order to maintain valid-
ity and reliability, the whole O-LIFE questionnaire was used.
The questionnaire assesses the following four dimensions: Un-
usual Experiences: reflects the positive symptoms of psychosis,
and consists of items assessing magical thinking, unusual per-
ceptual aberrations, and hallucinatory experiences (e.g., “When
in the dark do you often see shapes and forms even though
there is nothing there?”; “Are your thoughts sometimes so
strong that you can almost hear them?”). Cognitive Disorgani-
zation: reflects the disorganized aspect of psychosis, and con-
sists of items assessing difficulties with concentration and deci-
sion making, as well as social anxiety (e.g., “No matter how
hard you try to concentrate do unrelated thoughts always creep
into your mind?”; “Are you sometimes so nervous that you are
blocked?”). Introvertive Anhedonia: reflects the negative as-
pects of psychosis, and consists of items assessing the lack of
enjoyment from social contact, physical activities, coupled with
aversion to emotional and physical intimacy (e.g., “Are you
much too independent to get involved with other people?”;
“Are people usually better off if they stay aloof from emotional
involvements with people?”). Impulsive Non-conformity: con-
sists of items assessing aggressive, anti-social and impulsive
behaviour (e.g., “Were you ever greedy by helping yourself to
more than your share of anything?”; “Do you ever feel the urge
to break or smash things?”). The score for each scale is given
by the accumulated points across the items within the scale and
higher scores correspond to higher schizotypy.
J. BARNES ET AL. 373
Mean questionnaire scores are shown in Table 1. Using
SPSS, score distribution histograms showed normal distribution
and Pearson’s correlations and standard multiple regressions
were used. Correlation scores are shown in Table 2. There was
no evidence that Age was significantly correlated with any
measure. With respect to the schizotypy scale, the correlations
revealed a significant correlation between the scores on the
hallucination scale and Unusual Experiences, Cognitive Disor-
ganisation and Impulse Non Conformity. However there is no
significant correlation between scores on the hallucination scale
and Introverted Anhedonia. Stress score and sleep scores were
also positive correlate with the hallucinatory experience.
A linear regression analysis to test the extent to which stress,
sleep, age and schizotypy could predict differences in the hallu-
cination score (see Table 3). In these analyse, no significant
contribution was found for age or sleep, as a result these vari-
ables were not included in subsequent regression analyses. The
regression analysis results showed that, stress scores, Unusual
Experiences and Cognitive Disorganisation was significantly
positively correlated and were predictive of hallucinatory ex-
In partial accordance with our main hypotheses, aspects of
schizotypy, and stress, were predictive of hallucinatory tem-
perament. High levels of stress, unusual experiences, and cog-
nitive disorganisation were correlated with hallucinatory ex-
periences. Stress was the most prominently related which was
consistent with earlier reports of clinically-based research un-
derscoring the impact of emotional processes on the occurrence
of hallucinations (Fowler, Garety, & Kuipers, 1995; Slade,
1973). There was also a clearly established correlation between
the quality of sleep and tendency to experience hallucinations.
Hallucinatory occurrences related to sleep were previously
found in normal populations (Laroi, Van der Linden, &
Marczewski, 2004) and in clinical observations in which
symptoms related to poor sleep and levels of arousal were asso-
ciated with hallucinatory incidents (Barnes, Connelly, Wiggs,
Boubert, & Maravic, 2010). Not only does the ability to sleep
well contribute to physical and emotional health (Pilcher,
Ginter, & Sadowsky, 1997), it also serves as a predictor of
anxiety for the individuals in the study. Participants reported
continuing emotional disturbances, which in debriefing ap-
peared to be caused by their concerns that they might halluci-
nate while trying to fall asleep. It is conceivable, then, that in-
dividuals experience hallucination-like episodes might begin to
have difficulties sleeping due to an increase in anxiety that they
might hallucinate when going to sleep. This contribution that
anxiety has to the hallucinatory experience must be more
deeply examined, since it has been revealed that degrees of
anxiety tend to be lower as a hallucination ends, not higher, and
just before hallucination starts, we see a rise in anxiety, sug-
gesting there may be some contribution in the formation of the
hallucination (Delespaul et al., 2002).
The occurrence of hallucinations and schizotypy personality
traits had a normal distribution within the population, confirm-
ing the notion that hallucinations are widely experienced in
general population (Claridge & Beech, 1995). Introverted an-
hedonia did not appear to predict hallucinations. This indicates
that self-reported hallucination tendencies do not rely on per-
ceived sociability and that experiencing hallucinations has little
association with finding pleasure in social and physical interac-
tion. A positive association was also found between individuals
who are prone to hallucinate and individuals who experience
Cognitive Disorganisation, Unusual Experiences, and Impul
sive Non-conformity subdivisions of the O-Life. This suggests
that personality can be a strong predictor of the hallucination
Showing the mean values and standard deviation values for each of the
Questionnaire Mean Standard Deviation
Undergraduate Stress Questionnaire 26.3 11.4
Pittsburgh Sleep Quality Index 6.35 3.60
Launay Slade Hallucination Scale 13.6 8.67
Olife Total Score 32.6 11.9
Showing correlations o f m a in me a s ures.
Mean SD 1 2 3 4 5 6 7
1. Hallucination Score 13.69 8.675 1.000 .557** .365** .410** .002 .251** .407**
2. Stress Score 26.31 11.412 1.000 .461** .317** .038 .200* .366**
3. Sleep Score 6.35 3.602 1.000 .365** .305** .130 .239**
4. Cognitive Disorganisation 12.47 5.712 1.000 .178* .309** .381**
5. Introvertive Anhedonia 4.81 4.423 1.000 −.142 .005
6. Impulsive Non-Conformity 9.20 3.619 1.000 .204*
7. Unusual Experiences 6.13 5.370 1.000
*Correlation is significant at the 0.01 level; *Correlation is significant at the 0.05 level N = 127.
J. BARNES ET AL.
Linear regression analysis for hallucinatory experiences as measures
by Launay Slade Hallucination Scale.
Stress Score .422 5.433**
Unusual Experiences .163 2.054*
Impulsive Non Conformity .065 .855
Introvertive Anhedonia −.041 −.563
Cognitive Disorganisation .201 2.439*
F (5,121) = 16.14; R-squared = 0.406; Adjusted R-squared = 0.376; **Significant
at the 0.01 level; *Significant at the 0.05 level.
phenomenon and supports previous work that found a similar
relationship (Laroi & Van der Linden, 2005). The impulsive
non-conformity was found to correlate with the hallucination
scores but not to be predictive for hallucinations in the regres-
sion calculations. This finding may be explained with reference
to the shared variance between the O-LIFE dimensions, so that
when the effects of the other three dimensions had been taken
into account, impulsive non conformity was not predictive.
Thus people who experience hallucinations would be no more
likely than their peers to have unstable mood, or display disor-
ganized and socially inappropriate behaviour.
Overall, this study was able to demonstrate that stress and
schizotypy were able to account for variance in hallucination
scores. But we must observe that, even though we observed
consistent relationships, when we consider predictor variables,
there were other factors that appeared to be connected to hallu-
cinations when isolated and examined. This means it is possible
that, even though schizotypy and stress levels forecast halluci-
nations, there are obviously other individual differences, like
motivation and awareness for instance, that must be taken into
account. There were also a number of limitations which need be
acknowledged before an examination of the implications of this
study. The size of the sample was relatively small, and the al-
location of gender was not equal. Also, the most prominent
correlations might be partly the result of overlapping methods,
simply because self-reported measures forecast self-report
measures. The discovery that the hallucinations were not pre-
dicted by the Introvertive Anhedonia scale may be a reflection
of the negative facets of psychosis and consists of items that
evaluate anhedonia when socialising and suggests that with-
drawal from the social environment and being depressed are not
major factors in experiencing hallucinations.
In conclusion the findings of this study suggest that the lev-
els of stress and anxiety experienced by the participants were
the most influential predictors of a tendency to hallucinate.
Consequently, future investigations in this area might consider
rigorously examining the emotional predictors of a person’s
tendency to have hallucinations. This could involve more accu-
rate measures of stress levels, for instance, testing the cortisol
levels, as well as conducting interviews, and implementing
daily stress diaries maintained by the participant. In addition to
offering insight into the hallucinatory experience, it may also
shed light on the extent to which a person’s level of anxiety has
an impact on their tendency to have hallucinations.
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