ALTERED STATE S
DURING SENSORY ISOLATION IN .
TANK: IS THE IDGHLY SENSITIVE
VARIABLE OF IMPORTANCE?*
this study was to investigate
the highly sensitive personality
variable affects the occurrence
mystical experiences and degree
consciousness during sensory isolation in flotation-tank. Forty-eight
(20 males, 28 females ) were included. Background variables and
the Highly Sensitive Personality Scale
(HSP) were assessed. The independent
variable was derived from this scale, where two groups were forrned: low
sensitivity and high sensitivity. The treatment lasted
minutes in the
flotation tank. Dependent variables were assessed through scales measuring
experiences and degree
group with highly sensitive persons experienced significantly more mystical
experiences and higher degree
consciousness during the
treatment compared to the other group. Also, the highly sensitive persons
exhibited more stress and anxiety at arrival, but no differences in depression
and optimism were found between the groups.
grants from the county council
Värmland (Landstinget i Värmland),
research has followed the ethical standards
the World Medical Association declaration
conceming Ethical Principles
Medical Research Involving Human Subjects.
© 2009, Baywood Publishing Co., Ine.
Theory • Research • Clinical Practice
Editors: Robert G Kunzendoif, Ph.D.
James M. Honeyeutt, Ph.D.
Volume 29, Number 2 - 2009-2010
Altered States of Consciousness
Kjellgren, Andreas Lindahl, and Torsten Norlander
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136 / KJELLGREN, LINDAHL AND NORLANDER
Treatment in a flotation tank is a method where deep relaxation and stress
reduction are achieved. This treatment, often called flotation-REST (Restricted
Environmental Stimulation Technique),
a mild form
sensory isolation where
a person is irnmersed in a tank with salt water (magnesium sulphate) heated
temperature (35.5-36°C). Due to the high buoyancy
the saltwater, it
to float on the back in a relaxed comfortable position. There
and silence (ear-plugs are used) in the tank and this creates rest from normal
sensory stimulation. A common treatment session usually lasts for
Several studies, both earlier and more recent, have demonstrated excellent
treatment effects for symptoms where deep relaxation and stress reduction are
importance, like stress related pain, high stress load and "bum-out-depression."
The treatment effects in general are reduced muscle pains, reduced depression and
anxiety, as well as increased
and sleep quality [1-3].
Beside the deep relaxation, a
rtlild altered state
often achieved during the tank treatments. Some
the general characteristics
perception and body image, disturbed time sense,
alterations in cognitive functions, but also experiences that are best described
mystical and ineffable (e.g., ). Several kinds
have been described
during daydreaming, meditation, sensory deprivation, sensory overload, drug-
induced states, etc. There are obvious differences in the degree and intensity
experiences, depending on the condition that is being studied. A mild relaxation-
state naturally implies a different experience than a more dramatic
drug-induced state for example, but there also exist some common characteristics.
the most common experiences during a flotation-induced
inner mental imagery, sense
body image changes, as well as alterations ofthoughts and emotional expressions
in which deep personal insights might be achieved [3-5]. These states are usually
participants in studies
flotation-REST. Also, sometimes more
unusual mystical experiences occur, like out-of-body experiences, experienced
telepathy, hearing inner voices or music, perinatal experiences,
encounters with other beings, or transformations into animals
transcendence or transpersonal states imply access to
thoughts and experiences transcending the individual's biographic experiences
and thought-forms (thus the expression
We have performed research on clinical effects
flotation tank treatment at
the Human Performance Laboratory, Karlstad University in Sweden for several
years. Patients suffering from a wide array
symptoms like chronic muscle
tension pain, depression, and
"bum-out-syndrome" have been included in
different studies. The relaxation treatments in the flotation tank have been
great value for them, resulting in significant improvements and thorough psycho-
logical development and transformations [4, 6]. We have gotten the impression
CONSCIOUSNESS / 137
that the induction
might be a contributing factor to the healing
and transformation that often occur during flotation; persons obtaining deeper or
more mystical states
often seem to have extra benefit from the treatment,
but this has never been documented. Despite extensive search, we have not
find any specific personality variable that predicts such experiences
during the flotation tank treatment. Nor have we been able to find discussions in
the literature when it comes to mystical experiences during flotation-REST at all.
might be that this phenomenon
less important and therefore
not reported, or it might be that such experiences
not emerge at all or fail
attract any special attention.
Occasionally, participants in studies
the flotation tank express a desire
experience something beyond the normal state. However, a majority
ticipants in flotation tank treatment programs emphasize that they primarily
look forward to the peaceful relaxation without any disturbances. A general desire
stress reduction is likely to be a common
incentive among highly sensitive persons. The Highly Sensitive
(HSP), constructed by Aron and Aron , is a scale which includes a broad
items related to sensitivity. Highly sensitive persons are described
prone, from birth, to be easily overwhelmed
sensory stimulation, deeply
reflective, and unusually empathetic . Earlier research/studies with the
scale propose that persons with highly sensitive personality traits exhibit greater
susceptibility toward allergies, migraine headaches, chronic pain, and chronic
well as higher levels
anxiety , shyness [11, 12], and general
ill-health . We were interested in investigating
persons with a highly
sensitive personality (according to the scale) were more prone
or mystical experiences during
the present study was to investigate
the highly sensitive per-
sonality variable affects the occurrence
ofmystical experiences during flotation-REST.
females, were recruited among
students at Karlstad University, Sweden. Their mean age was
(SD= 7.63, range=
years). The participants were divided into two groups
based on low or high sensitivity (see Design section); statistical analysis with an
Independent samp1es t-test (S% level) did not showany differences in age between
the two groups. No differences in degree
sensitivity were found between
males and females in either the low or high sensitivity group
ehi-Square test (Goodness-of-fit,
level) did not
in the low sensitivity group
= 0.061), but there was such a difference in the
high sensitivity group
= 0.001) showing more females than men in this group.
138 KJELLGREN, LINDAHL AND NORLANDER
A flotation tank measuring 270 cm x 150 cm x
cm was used. The depth
fluid (salt water) varied from 200-to-300 mm. The flotation tank was insu-
to maintain a constant air and water temperature and to reduce incoming
light (complete darkness) and noise (ear-p1ugs for comp1ete silence). The water
temperature was maintained at 35.5-36°C and was saturated with magnesium
The treatment session lasted for
HAD - Hospital Anxiety Depression Scale
The RAD instrument measures the individual's degree
anxiety and depres-
sion. This instrument consists
statements regarding depression and
seven items regarding anxiety, with four response alternatives.
6 are considered normal, those between 6 and
are considered borderline,
points indicate a probable depression-anxiety diagnosis.
The validity and re1iability
RAD has been examined .
- Life Orientation Test
is a se1f-estimation instrument that assesses an individual's degree
dispositional optimism . The instrument consists
which each participant is instructed to the extent
statements fits in with himlher
an individual. The response alternatives are
presented on a 5-graded scale extending from O = "strongly disagree" to 4 =
"strongly agree." The test requires
out 5 minutes for completion. LOT is a
suitable scientific instrument with
estimated internal consistency
(Cronbach's alpha) and a Test-Retest reliability
0.79 (pearson's r), indi-
cating that the test result is stable over time. LOT
an adequate level
convergent and discriminant validity ,
by correlation statistics and by using LISREL VI
EDN - Experienced Deviation from Normal State
applied psychometric instruments APZ-questionnaire
and OA VA V  for obtaining judgments regarding altered states
sciousness, a shortened but similar instrument was modified for use with flotation
tank therapy . The original tests have been validated in
different countries . The shortened version utilized in the present study
questions, each followed
a Visual AnalogueScale (0-100 mm).
All points from the 29 items were averaged to form an "index
which reflects the total experience
deviation from normal states. The instrument
ALTERED STATES OF CONSCIOUSNESS / 139
acquired judgments regarding altered states (ASC). Cronbach's
when the instrument was apphed m
MES - Mystical Experience Scale
was constructed and validated by Hood . The
further validated by Hood et
. The scale consists
are divided into eight categories
mysticism: Ego quality (an mto
something greater than the empirical ego); Unifying. quaiity IS
"one"); Inner subjective quality (perception
or conscious); TemporaVspatial quality (time or space perceptIOn
Noetic quality (the experience gives a new understanding); (expen-
ence that cannot be put in words); Positive affect (posltlVe quahty
experience); and Religious quaiity (feelings or sacredness)
items have response alternatives on a 5-pomt ordmal The total P?mts
on the MES-sca1e range from 32 (least mystical) to
items are: "I have had an which was both
less and spaceless," "I have had an experience I knew to be sacred, "
have had an experience in which u1timate reality was revealed to me.
Cronbach's alpha in this study was 0.96.
- Perceived Stress Scale
used for measuring the perception
stress . The
measure how unpredictable, uncontrollable, and overloaded
their lives. There are also general questions about current perceptIOn
enced stress during the last month. Response alternatives on a
Likert scale from O (never) to 4 (very ofren). Examples
last month, how ofren have you felt nervous and 'stressed'?" the last
how ofren have you felt that you were
to control the Important thmgs
in your life?" The norm group for this scale gives a normal value
points for persons between 18-29 years .
- Highly Sensitive Person Scale
was used to assess. sensory
consists of27 questions with response alternatIves on a Likert scale 1 ( not
at all") to 7 ("extremely"). The points range from. 27 sensltlVe) to a
(most sensitive). Examp1es
questIOns Do you seem
subtleties in your environment?" "Are you easIly overwhe1med
strong sensory input?" Cronbach's alpha in this study was 0.84. Twoyersonahty
types were derived from the Highly Sensitive Person
50%: one group
and another group
individuals with the "high sensltlVlty personahty type.
140 / KJELLGREN,
The participants were recruited among students visiting the university
cafeteria. Inclusion criteria for participation were
be a full-time student
and not be on sick leave, and without previous experiences
flotation tank treatment. During the first visit
the laboratory, participants
were informed that participation was voluntary and that they could terminate
participating at any time without having
state a reason. At this first visit
some background data were gathered (age, gender) and the instruments
and RAD were filIed out. After this, some practical information about
flotation-REST (shower, toilet, ear-plugs) was given, and then they performed
a first treatment session
the equipment. The first
visit ended with a booking
the second visit.
During the second visit, a 45-minute treatment session in the flotation tank
was performed. After having showered and gotten dressed, participants answered
the instruments EDN and
MES. Participants were then thanked for participation,
and given a phone number in case any enquiries or questions should arise.
analyze background data obtained during the first visit, one-way
ANOV As were performed with Sensitive personality (low sensitivity, high sensi-
the indepep.dent variable and with Anxiety (RAD), Depression (RAD),
dispositional optimism (LOT) and Stress (PSS)
dependent variables. The
analyses revealed significant differences for Anxiety
45) = 6.47, p = 0.015)
= 4.61, p = 0.037), where the high sensitivity group showed
for both (Anxiety: M = 8.16,
= 2.97; Stress: M = 17.40,
= 5.60) compared
the low sensitivity group (Anxiety: M = 5.83, SD = 3.35;
Stress: M = 13.59,
= 6.57). There were
other significant effects. For means
and standard deviations, see Table
Experiences During the Relaxation in
the Flotation Tank
A one-way ANOV A with Sensitive personality (low sensitivity, high sen-
the independent variable and with EDN
the dependent variable
revealed a significant effect for the Sensitive personality
43) = 5.59, p = 0.023,
= 0.115), where the high sensitivity group had higher degree
= 15.70) than the low sensitivity group
Table 1. Means and Standard Deviations for Personality Variables
13.59 (6.57) 17.40 (5.60)
23.82 (3.82) 22.48 (4.34) 1.24
5.82 (3.35) 8.16 (2.97)
3.32 (2.06) 3.56 (2.64)
*Significant at the p = 0.05 leve!.
**Significant at the
A one-way Pillais' MANOVA with Sensitive personality (low sensitivity,
the independent variable and with the eight different sub-
scales in the MES-questionnaire and the MES-total
dependent variables was
performed. The analysis did not yield a elear significant effect for the Sensitive
= 0.053, eta) = 0.347, power = 0.79), but since the p-value was very
0.050 (indieating a non-significant trend), the univariate results are
presented' here. The univariate F-tests yielded significant effects for MES-total
= 10.70, p = 0.002); and for the following six subscales: Ego Quaiity
4.25, P = 0.045); Unifying Quaiity
44) = 4.71, p = 0.035); Noetic
44) = 6.18, p = 0.017); limer Subjective Quaiity
44) = 8.25,
p = 0.006); Religious Quality
44) = 4.10, p = 0.049); and TemporaVSpatial
44) = 4.05, p = 0.050), where the high sensitive group had higher
values for all these subscales and for MES-total (see Table 2). There were
significant results for Ineffability or Positive Affect subscales.
A Pearson correlation test was performed between HSP and the scales used
dependent variables in the present study. There was a significant positive
HSP and MES-total
= .336), and between MES-total and
(r = .422). The correiation between HSP and EDN was not significant
= 0.058), but quite near (see Table 3).
the present study was
the highly sensitive per-
sonaiity variable affects the occurrence
mystical experiences and degree
consciousness during sensory isolation in the flotation tank.
142 I KJELLGREN, LINDAHL AND NORLANDER
Means and Standard Deviations 'for the
High Sensitivity Groups for MES-total, the Eight Subscales in the
MES-questionnaire and EDN-scale
MES-total (mystical experiences)
Inner Subjective Quality
*Significant at the p = 0.05
**Significant at the p =
Table 3. Correlations (Pearsons') between HSP (total),
r = 0.279
P = 0.058
r = 0.336
P = 0.023*
significant at the 0.05
significant at the
r = 0.422
P = 0.003**
It was found that highly sensitive persons attained significantly higher degree
consciousness (as measured with EDN-scale)
more mystical experiences (MES-scale) than low sensitive persons during relax-
ation in the tank. We consider this very interesting since we have been studying
flotation-REST for several years but never have been able
personality variables (e.g., degree
ALTERED STATES OF CONSCIOUSNESS I 143
depression, stress, earlier experiences ofunusual states) that might influence the
consciousness and other more unusual psychological
experiences in the
tanle Also, in the present study, a correlation analysis between
the background personality variables and the dependent variables were per-
significant correlations were found
> 0.17); these results are
not shown in the results section.
we know, this might be the frrst time
a higher susceptibility toward attaining altered states
consciousness and also
mystical experiences in an experimental setting
person." A survey by Jawer  proposes that persons
with high sensitivity are more prone
have spontaneous paranormal experi-
ences. These findings are in line with our results.
Data from earlier studies
suggest that people with a highly sensitive per-
sonaiity are easily overwhelmed by sensory stimulation and also are more
sensitive toward a wide range
both outer and inner stimuli like hunger, pain,
light, noise, or other people's mood. AIso, highly sensitive persons are better at
detecting subtie differences in the environment. Tart [22, p.
points out that
consciousness "is a system that is stabilized in multiple ways,
integrity in the face
changing environmental input." During the
these stabilizing forces occur so the baseline
consciousness cannot maintain its integrity. During the stay in the
flotation tank, very few sensory stimuli are coming in, since the environment is
dark and quiet. Energy is then not required for dealing with these
stimuli and, according
Tart [22, p. 76], that freed energy might be used for
might be speculated that highly sensitive persons
not have the same robust stabilizing system for maintaining the normal state
low sensitive pers'ons have, and are therefore more easily
induced into altered states
consciousness during relaxation in the flotation
are more easily overwhelmed by the absence
possible explanation might be that a higher degree
reflects a more
'Complete relaxation for the highly sensitive persons in the peaceful environment
Significantly more mystical experiences (MES-scale) were also reported for
the highly sensitive group. A eloser look at the subscales
for six out
the eight subscales there were significantly more mystical expen-
ences among the highly sensitive group. Mystical experiences are one
experiences characterizing an
this is a further confirmation
increased inelination toward attaining more
among the high-HSP group.
There was a significant correlation between HSP-scores and MES-scores. The
HSP and EDN was quite close
= 0.058). The
MES and EDN was also significant.
course, no causal
relationships can be established solely through a correlational analysis, but it
might offer a hint
relatedness between the measures
consciousness, and the highly sensitive person scale.
144 I KJELLGREN, LINDAHL AND NORLANDER
From a historical perspective, altered states
consciousness might be con-
"the world's oldest healing method" (e.g., ). Ancient cultures and
native shamanistic societies have used consciousness altering techniques with
pw:pose to heal and create wellbeing for persons suffering from diverse
ailments. Such methods used for inducing
have inc1uded sensory isolation,
fasting, prayer, and also mind altering drugs. Even in our
might be considered as beneficiai and a
mechanism for healing (e.g., ). In earlier studies we have speculated that
induced by flotation-REST might, besides the deep relaxation, be a factor
partially contributing to all the
beneficiai treatment effects seen in flotation-REST
Our suggestions have been that the
induced during relaxation in the
tank might activate selfhealing systems
on a physiological
level (e.g., stress hormones decrease) but also on a psychologicallevel in which
thorough transformations can occur.
might offer possibilities for self-
discovery (e.g., identifying deep rooted (destructive) psychological pattems, or
another or bigger context).
this potential exists, it
special importance for highly sensitive persons, since this personality
variable seems to indicate a predisposition not only for poor physical health but
also for psychological suffering [25, 26]. Also in the present study it was found
that the highly sensitive group scored significantly higher on scales measuring
stress and anxiety than the low sensitivity group (but no differences regarding
depression and optimism). The values ofperceived stress for the high HSP-group
were higher than the norm group data and the values
anxiety were in the
borderline region for anxiety-diagnosis. The
low-HSP group values
anxiety were within the norm group range. Therefore flotation tank therapy might
extra beneficiai stress reduction technique for this group
in comparison to persons with lower
Significantly higher degree
consciousness and more mystical
experiences were assessed during 45 minutes
relaxation in a flotation tank
among persons scoring high on the highly sensitive person scale. All participants
in the present study were healthy persons. A suggestion for studies in the future is
performing similar investigations including persons
techniques like those suffering from muscle tension
pain or other stress-related
study could preferably inc1ude longer treatment series
a single flotation session.
(2007). Bending and mending the neurosignature. Frameworks
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ALTERED STATES OF CONSCIOUSNESS I 145
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G Kunzendorj, University
Honeycutt, Louisiana State University
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