An Investigation into Personality, Stress and Sleep with Reports of Hallucinations in a Normal Population—Hallucinations in Normal Population

doi:10.4236/psych.2011.24058

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Psychology

2011. Vol.2, No.4, 371-375

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.

Email: [email protected]

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

Introduction

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,

1988).

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.

372

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, &

Araujo, 2001).

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.

Methods

Participants

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)

Measures

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.

1989)

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

Results

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-

periences.

Discussion

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

Table 1.

Showing the mean values and standard deviation values for each of the

questionnaire scores.

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

Table 2.

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.

374

Table 3.

Linear regression analysis for hallucinatory experiences as measures

by Launay Slade Hallucination Scale.

Beta t

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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