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Sleep positions and personality: Zuckerman-Kuhlman's big five, creativity, creativity styles, and hypnotizability

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Abstract

Dunkell's (1977) pioneering work suggested possible associations between sleep positions and personality traits. We located only two studies since Dunkell's that provide general support to the notion that sleep positions may be reflective of personality. This study examined whether selected body positions at sleep onset, along with varied or do not know category, were associated with the selected personality characteristics. Participants were 332 psychology students. In contrast to findings from previous studies, the results supporting the relationship of sleep positions and personality were too weak, with small effects sizes, to be useful for any theoretical or clinical purposes.
________________________________
Author info: Correspondence should be sent to: V. K. Kumar, Department of
Psychology, West Chester University of Pennsylvania, 19383.
kkumar@wcupa.edu
North American Journal of Psychology, 2012, Vol. 14, No. 3, 609-622.
NAJP
Sleep Positions and Personality: Zuckerman–
Kuhlman’s Big Five, Creativity, Creativity
Styles, and Hypnotizability
Lincoln Z. Kamau
Elise Luber
&
V. K. Kumar
West Chester University of Pennsylvania
Dunkell’s (1977) pioneering work suggested possible associations
between sleep positions and personality traits. We located only two
studies since Dunkell’s that provide general support to the notion that
sleep positions may be reflective of personality. This study examined
whether selected body positions at sleep onset, along with varied or do
not know category, were associated with the selected personality
characteristics. Participants were 332 psychology students. In contrast to
findings from previous studies, the results supporting the relationship of
sleep positions and personality were too weak, with small effects sizes, to
be useful for any theoretical or clinical purposes.
Extant studies (e.g., Dunkell, 1977, 1994; Schredl, 2002) suggest that
the body, when we sleep, adopts various positions and these positions are
possibly related to individual differences in defense mechanisms,
everyday interactions with others, and personality characteristics
(Domino & Bohn, 1980). Furthermore, the use of different methods and
terms in these studies makes it difficult to draw general inferences about
the relationship between sleep positions and personality. The present
study was designed to comprehensively examine the relationships of
selected sleep positions with Zuckerman-Kuhlman’s big five
characteristics, hypnotizability, creativity, and styles of creativity.
Dunkell (1977) proposed that the location of hands, feet, heels,
ankles, wrists, elbows, calves, knees and thighs while asleep may carry
information concerning an individual’s personality. Also, the positioning
of buttocks when couples sleep together may communicate something
about their personality. Dunkell (1977) identified a wide variety of
preferred sleep positions, including the Full-fetal, Prone, Royal, Semi-
fetal, Chain-gang, Sandwich, Flamingo, Water Wings, Boxer, Mummy,
610 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
Sphinx, Monkey, Dutch Wife, Barrymore, Military Brace, Cat, and
Swastika. Dunkell reported that the Full-fetal Prone, Royal, and Semi-
fetal were the most common sleeping positions (1977), and these four
positions seem to have been most commonly evaluated across different
studies.
Dunkell (1977) observed that the (a) Semi-fetal sleepers were normal
and well adjusted, (b) Full-fetal and Prone sleepers were anxious and (c)
Royal position sleepers were self-confident. In a later publication,
Dunkell (1994, pp. 143-144) noted the Prone position sleepers to show
tendencies for impulsivity, obsessive-compulsive behavior, rigidity,
perfectionism, less sociability, and apt to “do well in professions like
banking, accounting, business and management.” The Royal position
sleepers were observed to be open, expansive, self-confident, and
sensation seeking. While the Semi-fetal sleepers were described as
conciliatory in nature, amenable to compromises, and unlikely to take
extreme stances, the Full-fetal sleepers were described as anxious and
emotional.
Domino and Bohn (1980), noting that Dunkell’s (1977) “evidence
consists of selected clinical cases and colorful anecdotes of
psychotherapeutic incidents” (p. 760), conducted an empirical study
examining the relationship between the California Psychological
Inventory and 14 drawings of sleep positions selected from Dunkell
(1977). Their participants were 51 “normal” (p. 760) females, ranging in
age from 17 to 41, who volunteered for a dream study. The participants
selected one position they typically used and then completed the
California Psychological Inventory. Six months later, the participants
selected a sleep position from the same, but randomly ordered, drawings.
Domino and Bohn (1980) reported that preference for sleep positions
was highly reliable inasmuch as 41 participants selected the same
position after 6 months; only 3 chose a different sleep position. Only one
person chose the prone position and none chose the royal position, a
result inconsistent with Dunkell’s (1977) observation that the four most
common positions are Full-fetal, Semi-fetal, Prone, and Royal.
However, they noted that they made no attempt to verify whether the
chosen sleep positions were indeed the ones used by their participants.
Six of the 14 sleeping positions were selected for statistical analysis
because they were the most common sleep positions reported: Semi-fetal
(n =13), Swastika (n =11), Dutch wife (n = 6), full fetal (n = 5), Flamingo
(n = 4), and Sandwich (n = 4). A one-way Analysis of Variance
completed for each of the 18 CPI scales across the six sleep positions
showed significant differences among the sleep positions on the
following CPI subscales: Sociability, Sense of Well-Being, Femininity,
Social Maturity, and Achievement by Conformance.
Kamau, Luber & Kumar SLEEP POSITIONS 611
Using post-hoc tests, Domino and Bohn found, consistent with
Dunkell’s (1977) observation, that the Full-fetal position was associated
with lower sociability and lower sense of well-being compared with other
positions. They also found, consistent with Dunkell’s (1977) observation,
that the Semi-fetal and Swastika positions (a variation of Semi-fetal
position) were reflective of better adjustment, as indicated by above
average scores on the social maturity.
Schredl (2002) investigated the relationship between body position at
sleep onset and personality dimensions associated with emotions in 47
psychology students (32 women and 15 men). Students completed a
sleep questionnaire and the German version of the 16-PF Personality
Inventory (Schneewind, Schroder & Cattell, 1983). One questionnaire
item elicited the position at sleep onset as detailed as possible including
the placement of the body, arms and legs. These descriptions were
classified into four groups: Semi-fetal (lying on side), Fetal (lying on
side, body curled up), Prone (face down), and Royal (lying on back).
Schredl (2002) found that the Semi-fetal and Fetal positions were
most common at sleep onset. Consistent with both Dunkell’s (1977) and
Domino and Bohn’s (1980) results, Schredl found the Prone position to
be associated with trait anxiety and less self-confidence, compared with
other positions included in the study. However, inconsistent with
Dunkell’s and Domino and Bohn’s results, Schredl did not find
significant differences between the Fetal and Royal positions on either
self-confidence or trait anxiety.
The Present Study
This study examined the relationship of selected body positions at
sleep onset, as reported by participants, and selected personality
characteristics in a more comprehensive way than studies reviewed
earlier. In addition to Zuckerman-Kuhlman alternative big five
personality dimensions (Neuroticism-Anxiety, Sociability, Activity,
Impulsive Sensation Seeking, & Aggression-Hostility), creative capacity,
creative styles, and hypnotizability were included in the study.
The alternative Zuckerman-Kuhlman’s five-factor model was chosen
because (a) there is much consensus concerning the Five-factor model
(Rossier, Meyer de Stadelhofen, & Berthoud, 2004), (b) the dimensions
are similar to the Big Five personality factors identified in lexical studies
(De Raad, 2000), and (c) there is biological basis to the alternative five
dimensions as to their heritability (McCrae, Jang, Livesley, Riemann, &
Angleitner, 2001).
The four sleep positions selected were those identified by Dunkell
(1977) as most common, namely: Full-fetal, Prone, Royal, and Semi-
fetal. Given that there are very few published studies on sleep positions
612 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
and personality, the present study must also be seen as exploratory.
However, the extant studies suggest some expectations for the present
study. The studies of Dunkell (1977), Domino and Bohn (1980), and
Schredl (2002) suggest that the Semi-fetal position would be most
popular and the Prone and Royal positions would be least popular.
Furthermore, the Semi-fetal position has been most associated in these
studies with adjustment, social maturity, self-confidence, and sociability.
Consequently, we expected individuals choosing the Semi-fetal position
to score higher on sociability, and general activity, but lower on
impulsive sensation seeking, aggression-hostility, and neuroticism
compared with individuals who choose other sleep positions. The
individuals choosing the Royal and Prone positions would be expected to
score higher on neuroticism, but lower on general activity and sociability,
compared with individuals who choose other positions.
The study also explored if sleep positions were associated with self-
perceived creative capacity, styles (beliefs and approaches to “being
creative”) of creativity, and hypnotizability. Self-perceived creative
capacity and styles of creativity were measured by Kumar and Holman’s
(1997) Creativity Styles Questionnaire-Revised and hypnotizability was
measured by Barber and Wilson’s (1977) Creative Imagination Scale.
Sleep Positions, Creative Capacity and Creativity Styles
If it can be assumed, per Dunkell (1994), that individuals showing
preference for the Prone position are rigid perfectionists, and individuals
showing preference for the Royal position are open and expansive, then
the former (Prone sleepers) would be more likely to report being less
creative than the latter (Royal sleepers).
Kumar and Holman (1997) identified seven styles of creativity: (a)
Belief in Unconscious Processes (e.g., needing to be in the right mood to
work; reporting having ideas without thinking about them); (b) Use of
Techniques (e.g., brainstorming, long walks, working on multiple ideas
simultaneously); (c) Use of Other People (e.g., consulting, working, and
sharing ideas or products with other people); (d) Final Product
Orientation (e.g., engaging in creative work to develop a final visible
product); (e) Environmental Control and Behavioral Self-Regulation
(e.g., setting up discriminative stimuli to facilitate creative work, i.e.,
choice of time, place, music, and use of mind altering substances); (f)
Superstition (e.g., wearing a favorite amulet or a piece of clothing, using
a favorite tool such as an easel, pen, or a thinking cap); and (g) Use of the
Senses (e.g., extent of use of the five senses for creative work).
Studies by Kumar and colleagues (Kumar, Holman, & Rudegeair,
1991; Kumar, Kemmler, & Holman, 1997; Lack, Kumar, & Aravelo,
2003; Manmiller, Kumar, & Pekala, 2005; Pollick & Kumar, 1997) have
Kamau, Luber & Kumar SLEEP POSITIONS 613
shown that individuals who view themselves as more creative tend to
report (a) greater belief in unconscious processes, (b) use a larger number
of techniques to a greater degree, and (c) tend to be intrinsically
motivated (i.e., are not final product oriented) when they engage in
creative efforts. However, there are no differences between those who
see themselves as more and less creative with respect to using other
people, designing special environments, and using strategies based on
superstition. Lack et al. (2003) found that fantasy prone individuals were
more likely to report being creative, and using Other People,
Environmental Control and Behavioral Self-Regulation, and
Superstition-based strategies for fostering their creative efforts.
Given the characterization of Prone sleepers as less confident,
anxious, rigid, perfectionistic, and less social, they would be less likely to
(a) believe in unconscious processes, (b) be intrinsically motivated, (c)
make use of other people in being creative, and (c) make use of
environmental control and behavioral regulation strategies. Given
Domino and Bohn’s (1980) results that the Semi-fetal position sleepers
were more sociable than Full-fetal position sleepers, it is likely that the
former would be more likely to make use of other people in their creative
efforts.
Sleep Positions and Hypnotizability
While historically some have viewed hypnosis as a sleep-like state
(see Kirsch, Lynn, & Rhue, 1993), to the authors’ knowledge no study
has looked at the relationship between sleep positions and
hypnotizability. Given that hypnotizability and creativity have been
characterized to involve imaginative processes, fantasy, and absorption
(see Manmiller et al., 2005), it is hypothesized that individuals preferring
the Royal position, characterized by Dunkell (1994) as open, expansive
and sensation seeking, would be most responsive to hypnotic
suggestions, relative to individuals preferring other positions.
METHOD
Participants
Participants were 332 students (Males = 93, Females = 239; Mean
Age = 20, Age Range = 18-39) from several psychology courses at West
Chester University. All students received credit toward completing their
research requirement for their respective courses. Nevertheless,
participation was voluntary and students were free to withdraw their
participation at any time during the study with impunity. Participants
were mainly Caucasian students (n = 300, 90.4%). The other ethnic
groups represented were 16 (4.8%) African American, 3 (0.9%) Asians, 6
614 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
(1.8%) Hispanic, and 2 (0.6%) American Indian, and 5 students did not
identify their ethnic group.
Instruments
Four questionnaires were administered to the participants.
Sleep Position. A single question was asked to measure the body
position at sleep onset. The instructions along with the options are as
follows:
When it’s time for you to sleep, which of the following best describes the
most comfortable position for you to fall asleep?
1. Lie on the side with the body curled upon itself. The legs are flexed at
the knees. The knees are drawn up as though attempting to touch the
chin, sometimes the entire body is rolled into a kind of ball. In some
instances the folded body position may curve around an object such as a
pillow, which serves as the core. Usually the arms and the hands
complete the circle enfolding the knees or being tucked in such a way as
further to cover the center of the body
2. Lie face down on the bed, usually with arms extended over their heads
and their legs stretched out with the feet somewhat apart.
3. Lie on my back.
4. Lie on the side with the knees drawn partway up.
5. Use varied positions or do not know.
The “1” through “5” descriptions correspond to the following sleep
positions: Full-fetal, prone, royal and semi-fetal.
Zuckerman- Kuhlman Personality Questionnaire (ZKPQ). The ZKPQ
is a measure of five personality factors, also described as the Alternative
Five-Factor Model, that emerged from factor analyses of personality
scales used in psychobiological research (Ball, 1995; Zuckerman, 2002;
Zuckerman, Kuhlman, Joireman, Teta & Kraft, 1993). The ZKPQ,
contains 99 items, uses a true-false response format for measuring
Neuroticism-Anxiety (fear, worry, emotional upset, tension, being
indecisive, having low confidence, and being sensitive to criticism);
General Activity (need for being active, busy life, challenging work; high
energy level, unable to relax and do nothing.); Sociability (outgoing,
many friends, spend time with friends, not preferring to be alone);
Impulsive Sensation Seeking (lack of planning, acting impulsively, need
for thrill and excitement, preference for unpredictable situations and
friends and the need for change and novelty in individuals), and
Aggression-Hostility (readiness to express verbal aggression, rude,
thoughtless or antisocial behavior, vengefulness and spitefulness, quick
temper and impatience).
The ZKPQ has been tested extensively for its psychometric
properties. It has demonstrated good internal consistency reliability (.74 -
Kamau, Luber & Kumar SLEEP POSITIONS 615
.84), test-retest reliability (.82-.87), validity and cross-cultural replication
(De Pascalis & Russo, 2003; Ostendorf & Angleitner, 1994; Shiomi,
Kuhlman, Zuckerman, Joireman, Sato & Yata, 1996; Wu, Wang, Du, Li,
Jiang & Wang, 2000; Zuckerman, 2002). The questionnaire has shown
consensual validity (Gomà-i-Freixanet, Wismeijer & Valero, 2005) and
concurrent validity. The ZKPQ appears to describe the characteristics of
drug abusers and predicts their success in therapy (Ball, 1995) and
predicts psychopathology (Gomà-i-Freixanet et al., 2008; O’Sullivan,
Zuckerman & Kraft, 1996; Thornquist & Zuckerman, 1995) and risk
taking (O’Sullivan, Zuckerman & Kraft, 1998; Zuckerman & Kuhlman,
2000).
Creativity Styles Questionnaire–Revised (CSQ-R). The CSQ-R
(Kumar & Holman, 1997) consists of 8 subscales: (a) Self-Perceived
Creative Capacity (SPCC) (b) Belief in Unconscious Processes; (c) Use
of Techniques; (d) Use of Other People; (e) Final Product Orientation; (f)
Superstition; (g) Environmental Control and Behavioral Self-Regulation;
and (h) Use of the Senses. On all subscales, higher scores suggest higher
amount of the attribute being measured. Thus, for example, for Final
Product Orientation, higher scores are indicative of extrinsic motivation
for creativity—that is, the person is motivated by the notion of
completing tangible final products and lower scores higher intrinsic
motivation..
The SPCC has yielded Cronbach α reliability values between .59 and
.76 (Median = .73) and evidence of convergent validity in five studies
(Fuchs, Kumar, & Porter, 2007; Lack, Kumar, & Arevalo, 2003;
Manmiller, Kumar, & Pekala, 2005; Pollick & Kumar, 1997). The range
and median Cronbach α reliability coefficients for the style subscales in
the aforementioned five studies were as follows: .65 to .75 (Median =
.67) for Belief in Unconscious Processes; .70 to .81 (Median = .77) for
Use of Techniques; .22 to .75 (Median = .74) for Use of People; .23 to
.45 (Median = .40) for Final Product orientation; .72 to .83 (Median =
.81) for Environmental Control and Behavioral Self-Regulation; .53 to
.72 (Median = .56) for Superstition; and .69 to .82 (Median = .73) for
Use of Senses.
The Creative Imagination Scale. The Creative Imagination Scale
(CIS) is a test of hypnotic responsiveness with high reliability and
validity (Barber & Wilson, 1977, 1978; Wilson & Barber, 1979). The
participants rate the 10 items of the scale as to how realistic their
responses were to each suggestion, using a 5-point scale (0-4). Kumar
and Farley (2009) using Smallest Space Analysis (SSA) to examine
structural aspects of the Creative Imagination Scale (CIS) suggested the
presence of one facet, focus of processing or variation in processing
requirements with two elements: somato-sensory and imagination-
616 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
sensory. The two subsets of items can serve as two subscales. Although
both sets of items require imagining experiences, the six somato-sensory
items all require making a movement and/or imagining some sort of
muscle movement, and imagining associated sensory experiences. In
contrast, the imagination-sensory items require no actual or imaginary
movements; instead, they require focusing on the experience.
Procedure
The participants were tested in groups. They completed an informed
consent form and answered the four questionnaires in the following
order: Sleep position, ZKPQ, and the CSQ-R. Afterwards, the “think-
with” instructions and 10 items of CIS were administered via a pre-
recorded audiotape to standardize the administration of the items. The
“think with” instructions are “designed to demonstrate how to think
along with the imaginative focus on the suggested themes” (Barber &
Wilson, 1977, p. 36). The participants then responded to the CIS
questionnaire.
RESULTS
Table 1 shows the means, SDs, and internal consistency reliability
values (Cronbach α) for each of the scales used in the present study. The
internal consistency reliability values were generally consistent with
values reported for the respective scales. The two scales with the lowest
reliability were Superstition and Final Product Orientation.
Table 2 displays the cross-tabulation of sex with sleep positions. The
pattern of frequencies was similar for both males and females (χ2 [4] =
6.51, p = .164]). Given that the χ
2
was not significant, sex was not
included in any of the subsequent analyses. The overall (across both
males and females) choice of positions differed significantly (χ2 [4] =
111.76, p =.0001]) with semi-fetal as the most popular sleep position (n =
136; 41.09%) followed by Prone (n =77; 23.26%), and then the Full-fetal
position (n = 51, 15.41%). The least chosen positions were Varied or Do
Not Know (n = 38, 11.48%) and Royal (n = 29, 8.76%).
To examine if the five sleep positions differentiated the five major
personality dimensions assessed by the ZKPQ scales, a Multivariate
Analysis of Variance (MANOVA) was performed. The analysis revealed
a significant effect over all five personality variables (Roy’s Largest Root
= .05, F[5,319]=2.99, p =.012). Consequently, further univariate analyses
were done on the five personality scales. Levene’s Test of Equality of
Error Variance was significant across the five sleeping positions groups
for the Impulsive Sensation Seeking Scale (F[4,320] = 2.44, p = .047 and
marginally significant for the Aggression-Hostility scale (F[4,320] =
2.26, p = .074). For all other scales, the assumption of the homogeneity
of variance assumption was met (F < 1.01, p > .41 in all cases).
Kamau, Luber & Kumar SLEEP POSITIONS 617
TABLE 1 Means, SDs and Internal Consistency Reliability Values for all
Instruments Used in the Study
Subscale
Cronbach α
M
SD
Neuroticism
.83
9.16
4.52
Activity .74 7.33 3.53
Sociability .81 9.97 3.96
Impulsive Sensation .78 9.64 3.93
Aggression .78 7.56 3.67
M/item SD/item
Self-Perceived Creativity
Capacity
.79 6.01 1.99
Belief in Unconscious
Processes
.67 3.22 .45
Use of Techniques .75 3.07 .49
Use of Other People .70 3.14 .66
Final Product Orientation .28 2.88 .48
Environmental Control .78 2.39 .53
Superstition .55 1.96 .84
Use of Senses .72 2.98 .77
Creativity Imagination
Scale
.75 28.52 6.87
The results of one-way analyses (see Table 3) on the five scales show
that there were significant differences among the means of the five sleep
positions on the General Activity Scale (F [4, 320] = 2.88, p = .023, η
2
=
TABLE 2 Cross-Tabulation of Sex with Sleep Positions
Full-fetal Prone Royal Semi-fetal Varied/DNK
Female 37 50 20 107 24
Male 14 27 9 29 14
N 51 77 29 136 38
Note: DNK = Do Not Know
.04). Post-hoc analysis (assuming Bonferroni p = .01 for 10 pairwise
comparisons for an overall α of .10, given small sizes), using the Fishers
Least Significant Difference test revealed none of the pairwise
618 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
comparisons to be significant. The analysis of variance also showed a
marginally significant effect on Neuroticism-Anxiety (F[4,320] = 2.28; p
= .06, η
2
= .028. Post-hoc analysis using the Fishers Least Significant
Difference (assuming Bonferroni p = .01 for 10 pairwise comparisons,
for an overall α of .10, given small sizes) test revealed a marginally
significant difference between the Full-fetal group (M = 10.44, p = .02))
and the Royal group (M = 8.00) and from the Varied or Do Not Know
Group (M = 8.00, p = .012).
A MANOVA on SPCC and the seven creativity styles scales revealed
no significant differences on any of the scales (Roy’s Largest Root =.04,
F =[8, 322] = 1.45, p =.175. Thus no further details are reported.
TABLE 3 Means (SDs) and ANOVA Results for ZKPQ Scales
N
Full
Fetal
50
Prone
74
Royal
29
Semi-
fetal
134
Varied/DNK
38
F
(p)
SOC 9.20
(4.3)
10.44
(3.6)
10.79
4.3)
9.74
(3.9)
10.02
(3.8)
1.17
(.32)
IMP 9.34
(4.5)
9.42
(4.0)
9.17
(3.0)
9.63
(4.0)
10.63
(3.5)
.83
(.51)
ACT 7.80
(3.0)
7.61
(3.8)
7.66
(3.8)
6.63
(3.5)
8.55
(3.4)
2.88
(.02)
AGG 8.14
(4.1)
8.28
(3.1)
6.55
(4.1)
7.22
(3.7)
7.56
(3.7)
1.86
(.12)
NEUR 10.44
(4.6)
9.55
(4.4)
8.00
(4.6)
9.17
(4.4)
8.00
(4.4)
2.28
(.06)
Note: SOC= Sociability; IMP= Impulsive-Sensation Seeking; ACT= Activity; AGG=
Aggression; NEUR= Neuroticism
A univariate analysis of variance did not reveal any significant
differences among the five sleep position groups on the CIS scale (F [4,
325] < 1.0). A MANOVA on the two CIS subscales Somato-Sensory
Activities and Imagination-Sensory Activities revealed no significant
differences (Roy’s Largest Root = .015, F[4, 310] = .1.18, p = .321.
Thus no further details are reported.
DISCUSSION
The results of the study were more supportive of the popularity of the
Semi-fetal position than that of the relationship between sleep positions
and personality. There was no evidence of sex differences on the choice
of sleep positions. Although overall results for two personality factors,
General Activity and Neuroticism, were significant, a consideration of
post-hoc comparisons and effect sizes suggest a very weak relationship
between sleep positions and personality.
Kamau, Luber & Kumar SLEEP POSITIONS 619
The Semi-fetal position was the overwhelming choice by both males
and females (41.08%)—a result consistent with those reported in the
Domino and Bohn (1980) and Schredl (2002) studies. However, this
similarity in results cannot be construed to indicate that the Semi-fetal
position is universally the most popular. The sample sizes in both
Domino and Bohn (1980) and Schredl (2002) were woefully small and
the differences between the Semi-fetal and other positions were not as
marked as found in the present study. The prone position was the second
highest in Domino and Bohn (1980), but not in Schredl’s (2002) study,
where the Royal and Prone positions were least chosen. The Full-fetal
was second most popular in Schredl (2002) study, but one of the least
popular in the Domino and Bohn (1980) study. In our study, it was third
most popular, with 15.41% of the participants choosing it.
There were two main expectations concerning differences on the
ZKPQ personality scales: (a) the Semi-fetal position would be most
associated with higher scores on General Activity and Sociability, and
lower scores on Impulsive Sensation Seeking, Aggression-Hostility, and
Neuroticism-Anxiety Scales; and (b) the individuals choosing the Royal
and Prone positions would be expected to score higher on Neuroticism-
Anxiety, but lower on General Activity and Sociability, compared with
individuals who choose other positions.
The results did not support either of the two expectations. Although
the analysis of variance revealed significant F values for General
Activity, none of the post-hoc comparisons reached significance. For
Neuroticism-Anxiety scores, the differences between the Full-fetal
position (M = 10.44) and the Royal (M = 8.0) and Varied or Do Not
Know positions (M = 8.0) were marginally significant. Furthermore, the
overall effect sizes were small (.04 for General Activity and .03 for
Neuroticism, per Cohen’s guidelines, see Sheskin, 2007). The results of
the present study also yielded no significant findings to indicate that
relationships exist between sleep positions, and self-perceived creative
capacity, styles (beliefs and approaches to being creative) of creativity,
and hypnotizability.
Clearly, more large-scale studies are needed. However, the
measurement of sleep positions needs to be standardized—there are so
many types used with so many variations of the same types that some
consensus is needed as to both the labeling and the descriptions of the
various sleep positions. Extant studies have varied in terms of what was
asked—position at sleep onset or typical sleep position used, yet another
aspect that needs standardization.
One definite lack in the literature on sleep positions is that the
investigators have not provided a sound theoretical rationale as to why
sleep positions should be associated with personality. It is possible that
620 NORTH AMERICAN JOURNAL OF PSYCHOLOGY
sleep positions may have an impact on the quality of sleep, which in turn
might have an impact on how one behaves during the daytime, such as
being irritable or pleasant. Koninck, Gagnon, and Lallier (1983) found
that sleep positions are indeed related to the quality of sleep. They
observed “poor sleepers” were more likely to sleep on their backs and
head straight for long periods of immobility, a position that is associated
with sleep difficulties and respiratory problems. They specifically noted
that “poor” sleepers scored higher on the MMPI scales of depression and
hysteria and higher on the Eysenck Personality Inventory’s neuroticism
scale. The “poor” sleepers also reported more awakenings at night,
spending more time being awake at night, and more agitation than did
“good” sleepers.
Although, the sample size in the present study was large (n = 332), it
was still limited in terms of the frequencies obtained for different sleep
positions, possibly limiting the power of statistical tests to detect
significant differences. The relationship of sleep positions to personality
does seem to have popular appeal as suggested by enthusiastic media
reports, complete with colorful labels and colorful descriptions of
sleeping positions and claims of their validity as predictors of
personality. Although the results of our study suggest that sleep positions
may be reflective of certain personality characteristics, the results were
very weak with small effect sizes and generally inconsistent with the
results of prior studies, raising questions about the extant media reports.
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Author Note: Lincoln Kamau is now a Board Certified Behavior Analyst (BCBA)
for the Plainfield public schools, Plainfield, Connecticut. The article is based on a
Master’s thesis of the first author. Elise Luber is a Compensation Analyst at UNI-
Select Inc, Buffalo, NY. We thank two anonymous reviewers for their helpful
comments on an earlier version of the paper.
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... Likewise, Yu's (2012Yu's ( , 2013 studies indicated that prone sleep, which creates pressure on the front of the body, may promote dreaming of sexual, erotomaniac, and persecutory material, such as themes involving "having a sexual relationship with a prominent person or celebrity, " "being smothered, unable to breathe, " and "being tied, unable to move." This effect cannot be properly accounted for by personality factors, which, similar to the findings reported by Kamau, Luber, and Kumar (2012), were shown to be weakly correlated with sleep position. In short, sleep position is a clinically significant issue in that it is associated not only with sleep-related disorders but also with other medical conditions and mental health factors. ...
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