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Effects of Flotation-REST on Muscle Tension Pain



The purpose of the present study was to investigate whether the floating form of the restricted environmental stimulation technique (REST) may be applied within the field of pain relief. Flotation-REST consists of a procedure whereby an individual is immersed in a tank filled with water of an extremely high salt concentration. Thirty-seven patients (14 men and 23 women) suffering from chronic pain consisting of aching muscles in the neck and back area participated in the study. They were randomly assigned to either a control group (17 participants) or an experimental group (20 participants). The experimental group received nine opportunities to use the flotation-REST technique in the water tank over a three-week period. The results indicated that the most severe perceived pain intensity was significantly reduced, whereas low perceived pain intensity was not influenced by the floating technique. Further, the results indicated that circulating levels of the noradrenaline metabolite 3-methoxy-4-hydroxyphenylethyleneglycol were reduced significantly in the experimental group but not in the control group following treatment, whereas endorphin levels were not affected by flotation. Flotation-REST treatment also elevated the participants' optimism and reduced the degree of anxiety or depression; at nighttime, patients who underwent flotation fell asleep more easily. The present findings describe possible changes, for the better, in patients presenting with chronic pain complaints.
Effects of flotation-REST on
muscle tension pain
Anette Kjellgren MSc1, Ulf Sundequist MA1, Torsten Norlander PhD1, Trevor Archer PhD2
1Department of Psychology, Karlstad University, Sweden; 2Department of Psychology, Göteborg University, Sweden
Correspondence and reprints: Dr Torsten Norlander, Department of Psychology, Karlstad University, SE-651 88 Karlstad, Sweden.
Telephone +46-54-83-91-65, fax 46-54-70-01-78, e-mail
Received for publication June 9, 2000. Accepted November 29, 2000
A Kjellgren, U Sundequist, T Norlander, T Archer.
Effects of flotation-REST on muscle tension pain.
Pain Res Manage 2001;6(4):181-189.
The purpose of the present study was to investigate whether the
floating form of the restricted environmental stimulation tech-
nique (REST) may be applied within the field of pain relief.
Flotation-REST consists of a procedure whereby an individual is
immersed in a tank filled with water of an extremely high salt
concentration. Thirty-seven patients (14 men and 23 women)
suffering from chronic pain consisting of aching muscles in the
neck and back area participated in the study. They were ran-
domly assigned to either a control group (17 participants) or an
experimental group (20 participants). The experimental group
received nine opportunities to use the flotation-REST technique
in the water tank over a three-week period. The results indicated
that the most severe perceived pain intensity was significantly
reduced, whereas low perceived pain intensity was not influ-
enced by the floating technique. Further, the results indicated that
circulating levels of the noradrenaline metabolite 3-methoxy-4-
hydroxyphenylethyleneglycol were reduced significantly in the
experimental group but not in the control group following treat-
ment, whereas endorphin levels were not affected by flotation.
Flotation-REST treatment also elevated the participants’ opti-
mism and reduced the degree of anxiety or depression; at night-
time, patients who underwent flotation fell asleep more easily.
The present findings describe possible changes, for the better, in
patients presenting with chronic pain complaints.
Key Words: Altered state of consciousness; Anxiety; Depres-
sion; Flotation; Life orientation test; Pain reduction; Restricted
environmental stimulation technique
Effets d’une technique de restriction des
stimuli environnementaux et de flottement
sur la douleur d’origine musculaire
RÉSUMÉ: Le but de la présente étude était de vérifier si le volet
flottement d’une technique de restriction des stimuli environnemen-
taux (technique REST pour restricted environmental stimulation
technique) peut s’appliquer au domaine de l’analgésie. La technique
de flottement-REST consiste à immerger le sujet dans un réservoir
empli d’eau à teneur extrêmement forte en sel. Trente-sept patients
(14 hommes et 23 femmes) souffrant de douleurs chroniques, soit de
douleurs musculaires au cou et au dos, ont pris part à l’étude. Ils ont
été assignés aléatoirement soit à un groupe témoin (17 patients) ou à
un groupe expérimental (20 patients). Le groupe expérimental a reçu
neuf occasions d’utiliser la technique de flottement-REST dans un
réservoir d’eau au cours d’une période de trois semaines. Selon les
résultats enregistrés, l’intensité douloureuse la plus grave perçue a
été significativement atténuée, alors que l’intensité douloureuse la
plus faible perçue n’a subi aucune influence de la technique de flot-
tement. En outre, les résultats ont montré que les taux du métabolite
circulant 3-méthoxy-4-hydroxyphényléthylèneglycol de la noradré-
naline était significativement diminué dans le groupe expérimental et
non dans le groupe témoin après le traitement, alors que les taux
d’endorphine n’ont subi aucune influence de la technique de flotte-
ment. Le traitement par flottement-REST a en outre stimulé l’opti-
misme des participants et réduit leur degré d’anxiété ou de
dépression. Au coucher, les patients soumis au traitement de flotte-
ment se sont endormis plus facilement. Ces résultats décrivent cer-
taines améliorations possibles chez les patients qui souffrent de
douleurs chroniques.
kjellgren’.qxd 1/3/02 10:29 AM Page 181
The current achievement-based, demanding, high tempo
society has incurred increased risks and vulnerability
for stress-related chronic pain and other illnesses. Increased
muscle tension facilitates the development of chronic pain,
and has been observed to induce negative effects on concen-
tration, self-confidence, learning and memory. The brain
and central nervous system undergo constant bombardment
with information. Relaxation exercises offer a means of
reducing the physiological and psychological reactions to
stress; however, the individuals most in need of relaxation
techniques are often those who find it most difficult to per-
form these exercises (1,2).
The flotation-restricted environmental stimulation tech-
nique (REST) is a method whereby an individual is placed
in a horizontally floating posture, immersed in high-concen-
tration salt water, in an environment (the floating tank)
where all incoming stimuli are reduced to the minimum dur-
ing a short period. The salt water in the floating tank is
maintained at skin temperature, ear-plugs are used to mini-
mize sounds, and when the tank is closed complete darkness
ensues. Flotation-REST is cost effective and secure, with
minimal or complete absence of adverse effects (3,4). The
method was developed by Lilly (5) in the 1950s, and no
accidents or mishaps have been reported with its use.
Previous reports concerning stimulus-reduction to the sen-
sory organs (sensory deprivation) indicated several negative
effects, such as confusion, worry and stress (6), whereas
more recent research has shown that meaningful, positive
effects may be obtained (7). However, several studies have
demonstrated positive effects, such as increased well-being
(8); mild euphoria (7); increased originality (9); improved
sleep (10); reduced stress, tension and anxiety (4,7,11);
reduced blood pressure (11,12); and less muscle tension
(13). The technique has also been shown to be a suitable
complement to psychotherapy (8,14). The experience is
pleasant, and subjects always endorse it on further occasions
Several studies have applied flotation-REST as a method
of alleviating different types of pain conditions. Patients
suffering from chronic headache experienced significant
improvements after flotation-REST treatment, and these
improvements were maintained during follow-up six
months later (16). Notable improvements in patients with
rheumatic aches were observed by Mereday et al (17).
Alleviation of premenstrual pain was noted by Goldstein
and Jessen (18). Other studies showing analgesic effects
associated with flotation-REST have been reported by Fine
and Turner (19), and Norlander et al (15). Attempts have
been made to identify the physiological markers for the sub-
jectively experienced pain alleviation that is often reported
with flotation-REST. Significant reductions in adrenocorti-
cotropic hormone and plasma cortisol levels have been
found after REST (20,21). One study (12) showed, in a
series of eight sessions, that REST was followed by a
decrease in plasma cortisol levels and a reduction in arterial
blood pressure compared with the initial treatment.
However, Schulz and Kaspar (7) did not find any changes in
plasma cortisol levels and other endogenous substances in
subjects 60 min after floating compared with lying on a mat-
tress for an equivalent period of time.
Flotation-REST is a technique that readily induces a state
of altered consciousness (22). This condition has been
described as a cognitive shift to the advantage of primary
process-oriented cognition (2,23). More logical thinking
and directed attention (secondary process) are shunted aside
by more intuitive thinking and nondirected fantasy (primary
process). To apply flotation-REST as a treatment or therapy,
it is essential that the personnel involved have sufficient
knowledge of the conditions being treated. The degree to
which a person experiences an ‘altered state’ is highly indi-
vidual. The most usual experience is likely one of calm and
pleasant relaxation, often in combination with a somewhat
altered perception of time (24). Other individuals experi-
ence, over and above this relaxation, a dream-like or hyp-
notic state (15), wherein slight perceptual or cognitive
alterations may occur. Visual phenomena, ranging from
spots, colours and lights to lively spontaneous images
(unwilled vivid imagery) have been described by Forgays
and Belinson (24), and Raab and Gruzelier (25). Lilly (5)
accumulated a comprehensive literature on mental experi-
ences in the floating tank. Norlander et al (15) reported that
flotation-REST can induce intense transpersonal experi-
ences that generally occur with altered states of conscious-
ness, despite the type of induction, but are perhaps strongest
in drug-induced states (26,27).
The purpose of the present study was to investigate
whether flotation-REST is an effective and reliable method
for treating chronic pain, as well as several psychosomatic
symptoms resulting from long term muscle tension and/or
stress-related headaches.
A portion of the participants were recruited through a
‘remission’ procedure (a procedure that allows patients
access to specialized treatment on recommendation from
their physician) from each one’s general practitioner. A por-
tion of the participants responded to announcements by the
Karlstad University, Sweden, for individuals suffering from
localized muscle tension pain in the neck and shoulder area,
with or without temporal headache, associated with myofas-
cial tender points (28) or trigger points (29,30). Each indi-
vidual was required to make an initial visit to the clinic,
where he or she was informed about the project, was
screened for suitability, and underwent a medical examina-
tion and a careful pain analysis, including palpation of mus-
cle status and neurological examination. Among the
exclusion criteria were pregnancy or ongoing breastfeeding,
somatic problems or illnesses requiring other types of treat-
ment, open wounds, manifest psychiatric symptoms, neuro-
logical disturbances, whiplash-related disorders, manifest
post-traumatic stress disorder, regular treatment with opiate
analgetics or sedatives, and signs of anxiety, fear or discom-
fort due to enclosure in a restricted environment. The 44
Kjellgren et al
kjellgren’.qxd 1/3/02 10:29 AM Page 182
subjects were randomly assigned to either the control group
or the experimental group. Five subjects in the experimental
group and two subjects in the control group withdrew from
the experiment. Therefore, the final experimental popula-
tion consisted of 37 subjects comprising a control group (17
subjects – seven men and 10 women) and an experimental
group (20 subjects – seven men and 13 women). The mean
age of the participants was 31.63 years (SD=9.87).
Approximately half of the participants (56.75%; 21
patients) presented with more than one type of pain com-
plaint, and almost the same number (51.36%; 19 subjects)
reported that the onset of pain had been immediate. One
subject (2.7%) reported that the pain had begun in associa-
tion with an illness (infection); seven subjects (18.92%)
indicated that ‘accidents’ (fall) were the cause of the pain.
Other causes named were ‘postoperative’ (two subjects;
5.41%) and ‘postphysical abuse’ (one subject; 2.7%), but
the majority of subjects reported the common causes of
myofascial pain, such as monotonous, repeated physical
strain or high demands. The participants’ earlier experiences
of pain treatment consisted of such methods as analgesics
(paracetamol, nonsteroidal anti-inflammatory drugs, opi-
oids), physiotherapy and acupuncture, the relative frequen-
cies of which are presented in Table 1. Approximately
one-third of the participants (14 subjects; 37.84%) reported
that they were taking an occasional paracetamol medication
(maximum 4000 mg during the three weeks) or ibuprofen
(one subject with a total of 1200 mg) during the course of
the experiment; these participants were from both the con-
trol and experimental groups. The subjects did not receive
any other type of medication treatment during the study
period. Sleep disturbances were reported by seven subjects
(18.92%; three control and four experimental). None of the
patients were receiving any other form of treatment (eg,
physiotherapy) during the study period. This stipulation was
ensured contractually and was monitored throughout the
The total frequencies of the reported health-related prob-
lems (eg, allergies, constipations, heart-flutters, neurologi-
cal deficiencies, breathing problems) were summated
(according to the information acquired at the initial medical
examination) to measure the ‘total burden’. A two-way
ANOVA with sex and groups as independent variables did
not show any significant differences between the groups or
any effect of the interaction (P>0.67). However, there was a
significant effect of sex (F[1,42]=10.90; P= 0.002), whereby
the female subjects (5.63±1.24 [mean ± SD]) had encoun-
tered a larger number of complaints than the male subjects
Statistical analysis through application of two-way
ANOVA with group and sex as independent variables did
not show any significant differences between groups with
regard to blood pressure, age, anxiety and depression scales
(Hospital Anxiety Depression Scale [HAD]), degree of dis-
positional optimism (life orientation test [LOT]), cigarette
and alcohol consumption, and self-estimations of the most
severe pain and normal pain, respectively (P>0.12).
However, there was a significant difference (F[1,42]=6.89;
P=0.012) between groups with regard to how long (number
of months) the pains had persisted, whereby the control
group had experienced pain during a shorter period
(41.03±38.68) than the experimental group (67.58±58.17);
it should be noted that longer durations of chronic pain may
have affected the pain sensitivity of the patients, but
whether this affects receptivity for the flotation treatment
remains to be resolved. A significant effect of sex was found
for anxiety (F[1,44]=7.702; P=0.008), whereby the men had
lower values for anxiety (5.94±2.82) than women
(8.93±3.75). No other significant differences were obtained
with regard to group and sex. Nor did Mann-Whitney U-
tests show any group or sex effects with regard to the use of
analgesics, other forms of therapy or how long the pain
symptoms had persisted (P>0.10).
The case history of the recruited participants was taken by
the physician (a senior physician in pain management) to
assess the status of the pain symptoms (using a combined
interview and questionnaire technique) and judge whether
each subject was free of exclusion criteria. Blood samples
were taken at that time. Subjects were then randomly
assigned to the control or experimental groups. Subjects in
the experimental group participated in a total of nine treat-
ments (three times per week during three weeks). Each
flotation treatment lasted 45 min, resulting in a total of
300 h of treatment. In addition to these treatments, each par-
ticipant was required to complete different types of ques-
tionnaires. After the last flotation treatment, a second
medical examination was made, incorporating new blood
samples and a follow-up of the assessment of pain status.
The control group was required to leave blood samples and
complete the initial questionnaires without flotation or any
other treatment and then returned for a further blood sam-
pling and examination of pain status after the identical
three-week period.
Flotation tank: The flotation tank (Flytarium Norden AB,
Sweden) measured 2620×1670×950 mm. The depth of fluid
(salt water) varied between 200 and 300 mm. The flotation
Flotation-REST and the pain experience
Incidence of previous treatment for chronic pain
Method n (%)
Analgesics 20 (54.05)
Other medications 7 (18.92)
Physiotherapist 29 (78.38)
Surgical/orthopedic treatment 2 (5.41)
Acupuncture 12 (32.43)
Transcutaneous electrical nerve 4 (10.81)
Relaxation training 15 (40.54)
Other treatments 19 (51.35)
kjellgren’.qxd 1/3/02 10:29 AM Page 183
tank was insulated to maintain a constant air and water tem-
perature, and to reduce incoming light and noise. The water
temperature was maintained at 34.4oC and was saturated
with magnesium sulphate (density 1.3 g/cm3). The tank was
equipped with a horizontal entrance that was easy to open
and close (from inside and out) by the subject. Between
flotations, a hydrogen peroxide solution was added regu-
larly, followed by filtration of the salt water and sterilization
with ultraviolet light. The number and duration of treat-
ments, ie, nine over a three-week period, were chosen from
similar schedules described in the literature. Another reason
for maintaining a three-week duration was that female sub-
jects participating could plan the timing of their flotation
treatments around the incidence of each menstrual cycle.
Blood sampling for women in the control group was sched-
uled in the same manner.
Questionnaire 1: At the initial medical examination, the
participants were given a form to estimate self-assessed pain
severity, duration, onset and treatment, as well as experi-
ences and symptoms of other types of complaints. Infor-
mation regarding sleep, dreams, tobacco and alcohol habits
was also collected. Each subject’s own descriptions of
‘severest pain intensity’ and ‘normal pain intensity’, respec-
tively, were estimated on visual analogue scales (0 to 100).
Questionnaire 2: Questionnaire 1 was given again at the
final medical examination, after three weeks of the experi-
mental flotation procedure.
HAD: The validity and reliability of the HAD scale for
assessing degree of anxiety and depression symptoms were
examined by Herrmann (31). The HAD scale measures the
degree of anxiety and depression, wherein values under 6
are considered normal, those between 6 and 10 are border-
line, and all values over 10 points are indicative of a proba-
ble depression-anxiety diagnosis.
LOT: The LOT test (32) consists of eight items, plus four
filler items. The task of each participant is to decide whether
one is in agreement with each of the items described, on a
scale of 0 to 4, where 0 indicates ‘strongly disagree’ and 4
indicates ‘strongly agree’. The test measures dispositional
optimism, defined in terms of generalized outcome
expectancies. Parallel test reliability is reported to 0.76 and
internal consistency to 0.76 (32). LOT is also regarded to
have an adequate level of convergent and discriminant
validity (32), demonstrated by correlation statistics and by
using LISREL VI (r=0.64).
Subjective flotation experience: Each subject was given a
questionnaire (15) to determine whether the flotation was
experienced as pleasant, whether the subject experienced
fear or anxiety during flotation, and whether the subject was
willing to float again. These responses were estimated on a
visual analogue scale (0 to 100). The severe flotation expe-
rience (SFE) form was applied directly after the first occa-
sion of flotation to evaluate how much each of the
participants ‘enjoyed’ the treatment. The dependent variable
measured (visual analogue scale 0 to 100) ‘how pleasant
was it to float?’, ‘how intensive was the experienced fear?’
and ‘to what extent would you like to float again?’.
Experienced deviation from the normal state: Using the
internationally applied psychometric instruments, the APZ
questionnaire and the OAVAV (6), for obtaining judgements
of altered states of consciousness, a shortened but similar
instrument modified for use with flotation-REST was
applied. The APZ and OAVAV forms are the internationally
applied standard for this purpose, and these tests have been
validated in several studies over different countries (33).
Because the test forms were originally intended for the
study of altered states of consciousness as induced by hallu-
cinogenic substances, a number of the original questions
were not relevant when flotation-REST was applied as the
method of induction. In total, the ‘experienced deviation
from the normal state’ (EDN) consists of 29 questions, with
responses marked on a visual analogue scale (0 to 100). The
major portion of these data are not applicable to the present
study, so only a part of the test results are presented here. A
complete ‘index of experience’ was constructed from the
points obtained from all 29 questions and were summated to
provide a ‘sum of experience’. These values should reflect
the total EDN.
Analysis of blood samples: The blood samples taken from
each subject were analyzed with regard to beta-endorphin
and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG),
the major metabolic product of noradrenaline, neurotrans-
mitter and hormone released under stress conditions. Opioid
peptide levels were determined by the radioimmunoassay
method described by Bramnert et al (34). MHPG was meas-
ured with high-performance liquid chromatography using
electrochemical detection described by Scheinin et al (35).
Participants experiencing pain, tension or headache were
recruited through noticeboard announcements at the
Karlstad University, Sweden. Some participants were
recruited through the ‘remission’ procedure (see above)
from their corporate or institutional health boards, as well as
from general practitioners, to take part in the project. Each
subject’s first contact with the project was during the inter-
view with the general practitioner at the initial medical
examination where the current status of pain complaints was
established through the application of questionnaire 1.
During this interview, each participant’s degree of anxiety-
depression was assessed using HAD to exclude individuals
with excessively high degrees of anxiety or depression.
After this, LOT was completed. Then, a blood sample was
taken for later analysis of beta-endorphin and MHPG. Every
participant received a leaflet with patient-oriented informa-
tion about flotation-REST, wherein, in addition to being
provided with the purely practical details associated with
treatment, they were informed that driving was not recom-
mended shortly after treatment (due to increased risk of
transient tiredness). During this initial contact, each subject
was shown around the floatarium, and participants were told
that those assigned to the control group would also receive
flotation treatment. The information was strict (no mention-
ing of possible changes in consciousness), and the partici-
Kjellgren et al
kjellgren’.qxd 1/3/02 10:29 AM Page 184
pants were only informed that most people find the floating
to be relaxing. Following this orientation, participants were
randomly assigned to either the control group or the experi-
mental group. Subjects in the control group were followed
up after three weeks with a new medical examination, where
they also completed questionnaire 2, HAD and LOT, and
gave a second blood sample. Subjects in the experimental
group underwent flotation treatment during the forthcoming
three periods (with three visits per week); each floating ses-
sion was of 45 min duration. The experiment was carried
out over four months at the flotation-REST laboratory,
Karlstad University. Group assignments were made by the
project leader and the resident physician. The project leader
never met any of the patients, and the resident physician
never met the patients in the context of flotation. The exper-
imenters at the flotation site were ignorant of the group
identity of each participant and thus, to all purposes, exper-
imentally blind. A ‘spontaneous randomization’ process
consisting of a ‘first come, first assigned’ method was
applied. When the subjects were using the flotation tank on
the very first session, they were informed of the floating
technique, shown the toilet and shower, and reminded that
they were free to terminate the session whenever they
wanted. After visiting the toilet, showering and inserting the
earplugs, each subject was allowed to immerse his- or her-
self into the tank and close the entrance of the tank unaided,
after having been instructed to relax. Treatment was termi-
nated after 45 min when the experimenter gently knocked
on the wall of the tank. Once the subject had emerged,
showered and changed clothes, he or she was required to
complete the SFE. An identical routine was maintained at
each succeeding treatment session. After the second flota-
tion session, each subject was required to complete the
EDN. Three days (or 72 h) after the final treatment session,
a new blood sample was taken when subjects met the gen-
eral practitioner for the second medical examination and
follow-up discussions, at which time they completed ques-
tionnaire 2, HAD and LOT using the same procedure as for
the control group. All the patients described in the present
study completed the entire course of treatment (ie, nine ses-
sions over three weeks). However, patients who abandoned
the treatment program were excluded at once and are
described as such above.
The dependent variables concerning both experimental
groups were analyzed with three-way split-plot ANOVAs,
with effects before and after treatment as the within-subject
factor, and group and sex as the between-subjects factors.
Three-way split-plot ANCOVAs with beta-endorphin con-
centrations before treatments as the covariate, and before
and after treatment as the within-subject factor (ie, MHPG,
pain intensity at its worst, ‘normal’ pain intensity, disposi-
tional optimism, depression, anxiety, number of hours of
sleep per night, time to sleep onset, experience of sleep
quality and blood pressure) were used to examine the extent
that beta-endorphin concentrations before treatments influ-
enced the results. The analyses did not yield any significant
effects other than those obtained through the ANOVAs,
which indicated that the difference between the groups with
regard to beta-endorphin concentrations did not influence
the above-mentioned within-subject factors. For means and
standard deviations see Table 2.
Analysis of blood samples
Beta-endorphins: There were no significant differences in
beta-endorphin concentrations before and after treatments,
or between the sexes (P>0.1), but higher beta-endorphin
concentrations were found in the control group than in the
experimental group (F[1,31]=4.41; Eta2=0.13; P=0.044).
MHPG: There was a significant difference in MHPG con-
centrations before and after treatments (F[1,31]=4.99;
Eta2=0.14, P=0.033], whereby MHPG concentrations were
lower after treatment than before. There was a significant
interaction effect between MHPG concentrations and group
before and after treatments (F[1,33]=4.19, Eta2=0.12,
P=0.049). Analysis of interaction (paired samples ttest, 5%
level) indicated that the experimental group had lower con-
centrations of MHPG after treatment than before. There
were no differences obtained before and after treatment for
the control group. No other interaction effects were
obtained, nor were there any other differences with regard to
group or sex (P>0.15).
Flotation-REST and the pain experience
Beta-endorphin (END), 3-methoxy-4-hydroxyphenyl-
ethyleneglycol (MHPG), severe pain (SPAIN), normal pain
(NPAIN), dispositional optimism (LOT), depression (DEP),
anxiety (ANX), and falling asleep time (FASLP) before (-1)
and after (-2) treatment with regard to group (control,
restricted environmental stimulation technique [REST])
Control REST Total
END-1 (pmol/L) 34.00±7.45 27.83±5.61 30.83±7.18
END-2 (pmol/L) 33.53±6.36 30.00±6.10 31.71±6.39
MHPG-1 (nmol/L) 10.18±2.74 10.83±4.22 10.51±3.54
MHPG-2 (nmol/L) 10.12±2.78 8.94±1.80* 9.51±2.37
SPAIN-1 (VAS) 59.06±17.68 61.75±18.78 60.51±18.08
SPAIN-2 (VAS) 60.41±17.21 37.25±30.22* 47.89±27.40
NPAIN-1 (VAS) 16.53±8.74 12.65±12.16 14.43±10.76
NPAIN-2 (VAS) 25.06±16.44* 12.20±14.55 18.11±16.55
LOT-1 (points) 21.88±6.22 22.25±5.42 22.08±5.72
LOT-2 (points) 22.76±6.07 24.95±5.22* 23.95±5.65
DEP-1 (points) 3.53±2.94 3.40±2.91 3.46±2.88
DEP-2 (points) 3.47±2.85 2.25±2.20* 2.81±2.56
ANX-1 (points) 7.94±3.65 7.50±3.32 7.70±3.43
ANX-2 (points) 8.18±4.53 4.95±4.11* 6.43±4.55
FASLP-1 (min) 19.21±15.15 13.98±13.66 16.38±14.40
FASLP-2 (min) 16.06±11.48 8.42±7.86* 12.03±10.34
Values are means ± SD. VAS Visual analogue scale. *Significant differ-
ence between before and after treatment
kjellgren’.qxd 1/3/02 10:29 AM Page 185
Experience of pain intensity
Pain intensity at its worst: The analysis indicated that
there was a significant difference in experienced ‘worst
pain’ before and after treatment (F[1,33]=6.90; Eta2=0.17;
P=0.013), whereby pain was experienced as being more
severe before treatment than after. There was a significant
correlation between group and pain before and after treat-
ment (F[1,33]=9.82; Eta2=0.23, P=0.004). Analysis of inter-
action (paired samples ttest, 5% level) indicated that the
experimental group experienced less severe pain after treat-
ment than before treatment. This was not the case for the
control group. There were no other interaction effects, and
no differences with regard to sex (P>0.25).
‘Normal’ pain intensity: The analysis indicated a signifi-
cant difference in experienced ‘normal pain’ before and
after treatment (F[1,33]=5.15; Eta2=0.14, P=0.030), with
pain being less intense before the treatment period than
after. There was a significant correlation between group and
‘normal’ pain before and after treatments (F[1,33]=5.04;
Eta2=0.13; P=0.032), whereby interaction analysis (paired
samples ttest, 5% level) indicated that the control group
experienced more pain after the treatment period than
before. In the experimental group, no significant differences
before and after treatment were found. No other interaction
effects were obtained, nor were any sex differences evident
Personality traits
Dispositional optimism: The personality trait dispositional
optimism was measured with the LOT-test. Results indi-
cated a significant change in optimism from before to after
treatment (F[1,32]=18.08; Eta2=0.37, P=0.001), with degree
of optimism increasing after treatment. There was a signifi-
cant correlation between group and optimism before and
after treatments (F[1,32]=5.755; Eta2=0.16; P=0.022),
where analysis of interaction (paired samples ttest, 5%
level) showed that the experimental group had a higher
degree of optimism after treatment than before treatment; no
difference between before and after treatment was seen in
the control group. No other significant differences with
regard to group and sex, or interaction effects were obtained
Depression: The results indicated that there was a signifi-
cant difference in depression assessment before and after
treatment (F[1,32]=5.51; Eta2=0.13; P=0.025); the degree of
depression was reduced after treatment. There was a signif-
icant correlation between groups and degree of depression
before and after treatments (F[1,32]=5.04; Eta2=0.12;
P=0.032). Interaction analysis (paired samples ttest, 5%
level) showed that the experimental group had a lower
degree of depression after treatment than before treatment.
There were no such differences in the control group. No
other results were significant (P>0.50).
Anxiety:. The analysis indicated that there was a significant
difference in anxiety before and after treatment
(F[1,33]=6.88; Eta2=0.17; P=0.013); level of anxiety
decreased after treatment. There was a significant correla-
tion between groups, and level of anxiety before and after
treatments (F[1,33]=9.87; Eta2=0.23; P= 0.04). Interaction
analysis (paired samples ttest, 5% level) showed that the
experimental group had a lower level of anxiety after treat-
ment than before treatment; no such differences were seen
for the control group. No other significant results were
obtained (P>0.11).
Number of hours of sleep per night: Participants were
required to indicate their duration of sleep before and after
treatment. There were no significant differences or correla-
tions (P>0.10).
Time to sleep onset: There was a significant difference in
time to sleep onset before and after treatment (F[1,32]=4.71;
Eta2=0.20, P=0.038). Time to sleep onset was shorter after
treatment than before treatment. There was a significant cor-
relation between time (minutes awake) and sleep onset
before and after treatments and group (F[1,32]=4.71;
Eta2=0.23; P=0.038). Interaction analysis (paired samples t
test, 5% level) showed that the experimental group fell
asleep more quickly after treatment than before treatment;
no similar difference was seen in the control group. Finally,
there was a group effect (F[1,32]=4.53; Eta2=0.17,
P=0.041), whereby the experimental group fell asleep more
quickly than the control group. No other significant differ-
ences were found.
Experience of sleep quality: Participants were required to
assess, on the VAS scale (0 to 100), their sleep quality
before and after treatment. Analysis did not indicate any sig-
nificant differences or interactions (P>0.16).
Cigarette and alcohol consumption: No significant differ-
ences in cigarette or alcohol consumption were found
(P>0.10) .
Blood pressure: A three-way split-plot analysis was used to
examine whether the participants’ blood pressures were
altered during treatment. The within-subjects factor was
systolic-diastolic blood pressure, and the between-subjects
factors were group and sex. No significant differences or
interactions were found (P>0.10).
Mental experiences during floating
Global notions about floating: Using the personality
inventory provided by the LOT (collected before treatment),
the participants were classified as either ‘optimists’ (more
than 23 LOT points) or ‘pessimists’ (fewer than 22 LOT
points). In addition, the participants were classified in a sim-
ilar manner as ‘low anxiety’ or ‘high anxiety’, and ‘low
depressive’ or ‘high depressive’, from the results of the
HAD test. Differences between optimists and pessimists,
between low and high anxiety, and between low and high
depressive, were analyzed on the SFE scales. One-way
ANOVA did not show any difference between optimists and
pessimists with respect to fear of floating or the extent to
which the subjects would like to float again (P>0.07). There
was a significant difference in the factor ‘how pleasant was
it to float?’ (F[1,24]=5.58; P=0.027); optimists experienced
Kjellgren et al
kjellgren’.qxd 1/3/02 10:29 AM Page 186
greater enjoyment (80.71±15.01) than the pessimists
(61.00±26.34). There was no significant difference between
participants with low anxiety and those with high anxiety, or
between those who were ‘low depressive’ and those who
were ‘high depressive’, respectively, regarding their experi-
ences of enjoyment, fear and wanting to float again (P>0.11).
Experience of altered state compared with normal state:
EDN forms were used to measure the extent of different
types of experiences. Every experience was measured as a
deviation from a normal state on a VAS-scale of 0 to 100.
Experiences that were most common were: ‘feeling of drift-
ing’ (68.2±31.88), ‘my body feels wonderful’ (65.72±26.89),
‘a dream-like time and space feeling’ (63.97±34.25), ‘a feel-
ing of deep peace within me’ (54.07±32.51) and ‘a feeling
of falling asleep’ (47.10±37.90). Feelings that occurred least
frequently were: ‘heard odd words’ (2.48±6.40), ‘heard tones
and clangs’ (7.00±14.57), ‘saw colours with my eyes closed’
(9.41±16.74), ‘received insights about previously puzzling
occurrences’ (10.42±21.13) and ‘came to think about things
that I’d forgotten long ago’ (10.52±19.79). No significant
differences (one-way ANOVAs) were seen between opti-
mists and pessimists, between those with low anxiety and
those with high anxiety, or betwen low depressives and high
depressives with regard to the summated experience of
deviation from a normal state.
Correlations (Pearsons’ r) between the most significant vari-
ables before (Table 3) and after (Table 4) were computed.
The main finding of the present study was that flotation-
REST induced a significant reduction of ‘severest’ pain
intensity, a significant decrease of noradrenaline metabolite,
MHPG, values in the blood, a significant reduction of anxi-
ety and depression concomitant with an increase in the
degree of dispositional optimism. In addition, a significantly
shorter latency to fall asleep at night was noted. The obser-
vation that the method was generally experienced as pleas-
ant suggests that flotation-REST should harness a large
positive potential for reducing pain and at least some of the
effects of chronic, negative stress.It should be noted that
several participants had suffered from pain for many years
and had been subjected to several types of treatment during
that period (Table 1).
A significant effect of pain alleviation was verified only
with regard to ‘severest experienced pain’ on comparison
before and after floating treatment, but not for ‘normal
pain’, which may not be obvious or apparent. It is most
likely that the flotation-REST technique maintains a pri-
mary pain alleviation effect for the experience of severe
pain and not for ‘normal’ pain. However, judging from all
the enthusiastic comments derived during the treatment
period, other explanations over and above the documented
effect should be examined. For example, it is possible that
the flotation-REST treatment affects ‘worst’ pain without
altering ‘normal’ pain. The answer to this dilemma may rest
with the patients’ experiences of these two types of pain.
Recent results (unpublished data) suggest that flotation-
REST affects the pain intensity experience of healthy vol-
unteer subjects.
Whether the significantly increased degree of optimism
(LOT test) seen in the present study was a consequence of
the pain-alleviating effect of the treatment, pleasantness, the
feeling of hope and enthusiasm engendered by the novel
technique, or some other mechanism is outside the scope of
this study. However, the connection here is interesting
because the patients (subjects) presented with pain in asso-
ciation with muscle tension or headache – a situation indica-
tive of a psychosomatic connection. Further, the established
degree of the reduction in anxiety and depression (the HAD
scale) also implicates a psychosomatic connection, with the
Flotation-REST and the pain experience
Correlation analyses (Pearsons’ r, corrected for the number
of comparisons according to Bonferroni) between the most
significant dependent variables after treatment: severe pain
(SPAIN), normal pain (NPAIN), beta-endorphin (END),
3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), anxiety
(ANX), depression (DEP), dispositional optimism (LOT) and
falling asleep time (FASLP)
SPAIN 1.00
NPAIN 0.55** 1.00
END 0.41* 0.24 1.00
MHPG 0.14 0.37 –0.01 1.00
ANX 0.12 0.30 –0.08 0.27 1.00
DEP 0.19 0.42* –0.01 0.23 0.65** 1.00
LOT –0.29 –0.28 –0.03 –0.11 –0.74**–0.71** 1.00
FASLP 0.22 0.40* –0.18 0.56** 0.49** 0.39* –0.30 1.00
*P<0.05; **P<0.01
Correlation analyses (Pearsons’ r, corrected for the number
of comparisons according to Bonferroni) between the most
significant dependent variables before treatment: severe
pain (SPAIN), normal pain (NPAIN), beta-endorphin (END),
3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), anxiety
(ANX), depression (DEP), dispositional optimism (LOT) and
falling asleep time (FASLP)
SPAIN 1.00
NPAIN 0.34 1.00
END 0.11 0.29 1.00
MHPG –0.17 –0.08 –0.16 1.00
ANX 0.19 –0.01 –0.18 –0.31 1.00
DEP –0.05 0.21 0.05 0.07 0.44* 1.00
LOT –0.24 –0.10 0.02 0.07 –0.69**–0.55** 1.00
FASLP –0.04 –0.23 –0.02 0.07 0.35 0.39* –0.22 1.00
*P<0.05; **P<0.01
kjellgren’.qxd 1/3/02 10:29 AM Page 187
potential for reducing anxiety and depression. It should be
noted that ‘optimists’ found the treatment to be more pleas-
ant than ‘pessimists’. These observations agree with earlier
reports demonstrating that flotation-REST is a technique
that increases well-being, and decreases tension and anxiety
(7,8,13,19). Further associations among personality vari-
ables and overall experiences are presented in Table 4,
which indicates that the time to fall asleep correlated with
MHPG, anxiety and depression. This observation is relevant
because alterations in noradrenaline neurotransmission and
metabolism, and sleep difficulties have been implicated in
anxiety and depression. Additionally, it was found that the
personality trait of dispositional optimism (as indexed by
the LOT test) correlated negatively with depression and
anxiety (as indexed by the HAD scale). This relationship
between LOT and HAD does not provide new insights into
flotation-REST as a method for pain relief but may indi-
rectly confirm the validity of each test. However, there is no
sure means of ascertaining the extent to which the partici-
pants’ pain complaints were of a psychosomatic nature.
Gustafson and Källmén (36) found that pain patients
showed higher manifest anxiety than patients presenting
with pain judged to be of a clearly somatic type. If this is the
case, pain reduction may induce anxiety-reducing and gen-
eral antidepressive effects.
Flotation-REST has been employed in the treatment of
sleep problems (10). In the present study, there were no
changes with regard to either the duration of sleep or the
quality of sleep, but there was a significant reduction in the
time taken to fall asleep. One condition for falling asleep is
being able to relax. Thus, the present result supports the
possibility that flotation-REST suppresses anxiety and the
generation of negative emotional patterns, and facilitates the
acquisition of more effective relaxation techniques. In this
regard, it should be noted that the control patients had to
remain on a waiting list for the flotation-REST treatment.
Thus, it is possible that at least a part of the ameliorative
effects may not be due to flotation-REST but that a more
general effect might have been induced by the attention the
patients received, by a higher level of activity/engagement
(ie, leaving home nine times in three weeks), and possibly
increased levels of self-efficacy (see LOT result), attention-
placebo (ie, receiving the same amount of attention from the
experimenters involved), etc. It is unfortunate that no fol-
low-up procedure, particularly one reversing the control and
experimental groups for flotation-REST, was incorporated
in the experimental design; this might have indicated the
longevity of effects, from which the clinical and economical
utility might have been noted.
It is possible that the observed pre- to post-treatment
reduction in the noradrenaline-metabolite MHPG reflects an
altered stress-relaxation relationship in these individuals.
However, it must be noted that circulating levels of nor-
adrenaline are known to modulate pain thresholds (37). In
the present study, endorphin levels were not affected
directly, although, for unknown reasons, the control group
indicated higher levels than the experimental group at both
pre- and post-treatment measurements. There were no meas-
ures of serotonin metabolites in the present study. There is a
vast amount of evidence not only for the role of serotonin in
the pharmacology of pain but also for the intricate seroton-
ergic-noradrenergic interactions (38), while the relative
roles of these neurotransmitter systems is evident in stress-
induced analgesia (39). Further, serotonergic mechanisms
have been shown to be involved in beta-endorphin-mediated
analgesia (40). Thus, it is imperative that further investiga-
tions of flotation-REST efficacy in chronic pain alleviation
include measures of the serotonin metabolite 5-hydroxyin-
dole acetic acid.
Independent of whether flotation-REST influences levels
of endorphins, other biologically active markers may be
directly or indirectly affected by the treatment, possibly
through a complex array of feedback mechanisms.
Independent of which circulating biological markers may be
implied in the experienced pain reduction, it is necessary to
consider which changes represent cause and effect, respec-
tively. Altered concentrations of endogenous compounds
may trigger or be triggered by deeply underlying psycho-
logical functioning that may be influenced by situations in
which an individual experiences an altered state of con-
sciousness or deep relaxation.
The most common experiences that were deviations from
a normal state were: ‘feeling of floating’, ‘my body feels
wonderful’, ‘dream-like alteration of time and space per-
spective’, ‘feeling of intense peace’ and ‘feeling of falling
asleep’. These experiences may largely be described as a
pure relaxation effect. Subjects who experienced ‘inner
images/visions and noises/voices’ and experiences charac-
terized by ‘unity, limitless, religious’ have emerged from
more intense experiences than those that have been
described as pure effects of relaxation.
The results of the present study tentatively suggest that
flotation-REST may offer an effective method of alleviating
low to moderately severe pain induced by muscle tension.
Further investigations are aimed at extending the scope of
the subjective changes and the neurochemical markers (eg,
with the serotonin metabolite 5-hydroxyindole acetic acid,
oxytocin and cortisol) followed by a comprehensive six-
month follow-up investigation.
ACKNOWLEDGEMENTS: This article was supported by grants
from Karlstad University, Sweden. The study has had ethical
approval from the Ethical Board on Experimentation on Human
Subjects (Forskningsetikkommittén) at Karlstad University.
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... The acute effect of this intervention appears to be one of heightened interoceptive awareness for cardiorespiratory sensations in the context of physiological relaxation, including reductions in blood pressure and muscle tension (Feinstein, Khalsa, Yeh, Al Zoubi, et al., 2018b;Turner, Gerard, Hyland, Nieland, & Fine, 1993;Turner & Fine, 1983;Van Dierendonck & Te Nijenhuis, 2005). Subjectively, Floatation-REST has been shown to elicit short-term decreases in states of negative affect (e.g., anxiety, depression, and pain) and increases in states of positive affect (e.g., feeling refreshed, serene, and relaxed) (Feinstein, Khalsa, et al., 2018a;Forgays & Belinson, 1986;Jacobs, Heilbronner, & Stanley, 1984;Kjellgren, Sundequist, Norlander, & Archer, 2001). To date, no neuroimaging studies have explored the neural effects of Floatation-REST, and in general, little is known about how the nervous system responds following a prolonged period of reduced sensory and motor stimulation. ...
... Floatation-REST has been found to have short-term anxiolytic, antidepressant, and analgesic effects (Bood et al., 2006;Feinstein et al., 2018a;Kjellgren et al., 2001), yet little is known about how the intervention impacts brain networks such as the DMN. Subjectively, the intervention has been found to induce altered states of consciousness, often described as a liminal state, somewhere between being asleep and awake (Kjellgren, Lyden, & Norlander, 2008). ...
... The posterior insula is closely connected with both the somatosensory cortices and the posterior cingulate (Cauda et al., 2011;Deen et al., 2011), creating a strong interconnected system between hubs of the posterior DMN and the somatosensory cortices. Since Floatation-REST has been shown to significantly reduce muscle tension (Feinstein et al., 2018b;Kjellgren et al., 2001), it may be possible that the intervention directly alters the representation of this tension within the brain's body maps. This is consistent with a prior fMRI study that found reduced activity in the posterior cingulate, somatomotor, and insular cortices following progressive muscle relaxation (Kobayashi & Koitabashi, 2016). ...
Full-text available
Floatation‐Reduced Environmental Stimulation Therapy (REST) is a procedure that reduces stimulation of the human nervous system by minimizing sensory signals from visual, auditory, olfactory, gustatory, thermal, tactile, vestibular, gravitational, and proprioceptive channels, in addition to minimizing musculoskeletal movement and speech. Initial research has found that Floatation‐REST can elicit short‐term reductions in anxiety, depression, and pain, yet little is known about the brain networks impacted by the intervention. This study represents the first functional neuroimaging investigation of Floatation‐REST, and we utilized a data‐driven exploratory analysis to determine whether the intervention leads to altered patterns of resting‐state functional connectivity (rsFC). Healthy participants underwent functional magnetic resonance imaging (fMRI) before and after 90 min of Floatation‐REST or a control condition that entailed resting supine in a zero‐gravity chair for an equivalent amount of time. Multivariate Distance Matrix Regression (MDMR), a statistically‐stringent whole‐brain searchlight approach, guided subsequent seed‐based connectivity analyses of the resting‐state fMRI data. MDMR identified peak clusters of rsFC change between the pre‐ and post‐float fMRI, revealing significant decreases in rsFC both within and between posterior hubs of the default‐mode network (DMN) and a large swath of cortical tissue encompassing the primary and secondary somatomotor cortices extending into the posterior insula. The control condition, an active form of REST, showed a similar pattern of reduced rsFC. Thus, reduced stimulation of the nervous system appears to be reflected by reduced rsFC within the brain networks most responsible for creating and mapping our sense of self.
... As a consequence, mechanical, thermal, visual, and acoustic stimuli are reduced to a minimum. Previous studies have shown positive effects of flotation-REST, such as increased relaxation, 13 lowered stress levels, 14,15 improved sleep quality, 16 reduced anxiety, 14,15,17,18 and pain relief. 15,19 These studies, however, differed in design, sample size, inclusion criteria, and dosage of flotation-REST, which hinders their comparison. ...
... As a consequence, mechanical, thermal, visual, and acoustic stimuli are reduced to a minimum. Previous studies have shown positive effects of flotation-REST, such as increased relaxation, 13 lowered stress levels, 14,15 improved sleep quality, 16 reduced anxiety, 14,15,17,18 and pain relief. 15,19 These studies, however, differed in design, sample size, inclusion criteria, and dosage of flotation-REST, which hinders their comparison. ...
... Previous studies have shown positive effects of flotation-REST, such as increased relaxation, 13 lowered stress levels, 14,15 improved sleep quality, 16 reduced anxiety, 14,15,17,18 and pain relief. 15,19 These studies, however, differed in design, sample size, inclusion criteria, and dosage of flotation-REST, which hinders their comparison. Several studies have examined the effects of flotation-REST on chronic pain, [14][15][16]19,20 but the effects on chronic pain lasting more than 72 hours were only assessed once. ...
Full-text available
Importance Flotation restricted environmental stimulation therapy (REST) is an emerging therapeutic intervention that, to our knowledge, has never been directly compared with an indistinguishable placebo in patients with chronic pain. Objective To determine whether 5 flotation-REST sessions alleviate chronic pain. Design, Setting, and Participants This single-blind, randomized clinical trial compared flotation-REST as an intervention for the treatment of chronic pain with indistinguishable placebo and wait-list control conditions at Hannover Medical School, Hannover, Germany. Men and women aged 18 to 75 years who had been diagnosed with chronic pain disorder with psychological and somatic factors (International Statistical Classification of Diseases and Related Health Problems, 10th Revision, German Modification, code F45.41) by physicians at the study center were randomly assigned to 1 of the 3 groups. Data were collected from June 26, 2018, to June 18, 2020. Interventions Patients in the intervention and placebo groups underwent 5 treatment sessions lasting 60 to 90 minutes, each session separated by 4 days. The placebo treatment was delivered in the same floating tank but controlled for effortless floating and environmental stimulus restriction. Patients in the wait-list control group did not receive any additional treatment but were asked to continue any ongoing treatments at the time of enrollment. Main Outcomes and Measures The primary outcome was a change in pain intensity 1 week after the last treatment session. The assessment was repeated at 12 and 24 weeks. Secondary outcomes included pain-related disability, pain area, pain widespreadness (number of body regions affected by pain), anxiety, depression, and quality of life, as well as several other short-term outcomes. Results A total of 99 patients (mean [SD] age, 51.7 [12.3] years; 80 women [81%]) were included in the study. No differences were found among the groups in the primary outcomes (mean [SD] change in maximum pain: −7.6 [19.7] for the intervention group, −5.8 [12.7] for the placebo group, and 0.4 [14.0] for the wait-list control group; mean [SD] change in mean pain: −2.1 [19.4] for the intervention group,−4.2 [16.2] for the placebo group, and 2.0 [12.6] for the wait-list control group). Long-term secondary outcomes did not show significant differences. In the short term, patients in the intervention group showed significant improvements in pain intensity (−17.0 [17.1]; P < .001), relaxation (23.9 [22.6]; P < .001), anxiety (−10.1 [8.4]; P < .001), pain area (−3.6% [7.4%]; P < .001), and widespreadness (−2.0 [3.0]; P < .001), and similar changes where observed in the placebo group. Conclusions and Relevance Patients with chronic pain experienced no long-term benefits from the 5 flotation-REST interventions. Clinically relevant short-term changes in pain in the placebo group suggest that improvements may not be caused by environmental stimulus restriction or effortless floating as previously thought. Trial Registration Identifier: NCT03584750
... Modern research on flotation-REST has established a treatment protocol consisting of 12 flotation sessions (each of 45 minutes) over a 7-week period, and this has been suggested as sufficient to reach therapeutic effect when used as an intervention for chronic pain conditions as well as stress related ailments 6 . Contemporary research on flotation-REST has indicated this method as a promising treatment for chronic pain conditions 7,8 , stressrelated ailments 9,10 , generalized anxiety disorder 11 , as well as a preventive health care intervention 12 . In addition, a meta-analysis has indicated flotation-REST primarily as an effective method for stress reduction, increasing well-being, and performance enhancement 13 . ...
... For example, studies have reported increased post-treatment sleep quality for healthy workers 12 (a non-psychometrically tested scale with 11 items), people with stress problems 9 ("rate your sleep quality from 0-100%"), people with burnout syndrome 16 (a non-psychometrically tested scale with 11 items), and people with generalized anxiety disorder 11 (the Pittsburgh sleep quality index). People with chronic pain reported shorter sleep onset latency, but no changes in sleep duration after therapy in one study 8 . Only one previous study has investigated the effects from flotation-REST on people with primary insomnia. ...
Objectives: Flotation-REST is a treatment for deep relaxation, where a person is contained in a stimuli-restricted environment and floats in water with high salt content. The aim was to investigate the effects from flotation-REST on people with insomnia diagnosis, as previous studies of flotation-REST have demonstrated some effects on sleep but have limitations regarding sample selections and sleep measures. Material and methods: Six participants were recruited through an outpatient psychiatry clinic and posters on a university campus. All participants fulfilled criteria for insomnia diagnosis and four fulfilled criteria for major depressive disorder. Using a single case experimental design, daily changes were investigated on sleep logs regarding sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST), and sleep efficiency over the course of 12 sessions consisting of 45 min of flotation-REST. No other treatments were offered simultaneously. Questionnaire data on insomnia severity (the ISI) and depressive severity (the MADRS) were also collected. Results: Three participants improved on their most salient insomnia symptom (long SOL or WASO), and two improved on sleep efficiency. The improvements were maintained 2 months after treatment. Insomnia severity decreased for three patients, whereas depressive severity decreased for five. No changes in TST were found and two patients did not improve on any sleep measure. The two participants who benefitted the most were students in their 20s. Discussion: The results were mixed. Flotation-REST may be beneficial for young adults with sleep-onset insomnia but more research is warranted.
... Individuals floated 9 times during a 3-week period. 12 In a Swedish study, 32 individuals with physician-diagnosed muscle tension pain related to stress participated. Specific aspects taken into consideration included number of pain areas and intensity, duration, and frequency of pain. ...
... 19 Kjellgren et al observed that floating did not appear to alter the quality or duration of sleep in a study involving 37 patients, but it was found to significantly shorten the length of time needed to fall asleep. 12 This may be related to the relaxation and anxiolytic effects of floating. Future studies with magnesium supplementation compared to, or in addition to, floatation therapy will be beneficial. ...
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The purpose of this article is to introduce healthcare providers to the concept of floatation therapy. This paper explores which types of patients will most likely find floating beneficial for specific health challenges. In addition, it discusses patients who should avoid floatation therapy.
... Kjellgren 2017). Die vorhandenen Studien zu Floatation-REST geben klare Hinweise auf eine zumindest kurzfristige anxiolytische, antidepressiveund schmerzlinderndeWirkung (Feinstein et al. 2018;Kjellgren et al. 2001). Auffallend sind nach der Floatation-REST-Erfahrungnichtnur einetiefeEntspannung und ein Erfrischungsgefühl, sondern auch ein vermindertes Gedankenkreisen. ...
In dieser theoretischen Arbeit soll versucht werden, das Rätsel der subjektiven Zeit in gewöhnlichen und außergewöhnlichen Bewusstseinszuständen (ABZ) mit der Selbstwahrnehmung zu erklären. Die Erfahrung der Veränderlichkeit des Zeitverlaufs ist in ABZ noch extremer ausgeprägt. Dort kommt es zu einer gemeinsamen Modulation der Zeit und des Selbst. Die veränderten Zeit- und Selbsterfahrungen von Patienten mit psychischen Erkrankungen der Depression, Angst und Substanzabhängigkeit – eine Überrepräsentation der Zeit und des Selbst – sollen in einen Kontext möglicher komplementärer Interventionen wieMeditation, Floatation-REST (Restricted Environmental Stimulation Technique) und Psychedelikaanwendungen gesetzt werden; diese basieren auf den skizzierten psychologischen und neuronalen Grundlagen der Zeit- und Selbstwahrnehmung.
... This sensation may at least be contributory to feeling a sense of peace in some cases because experients can in such a state feel free from the normal confines of the physical body. Research has shown that people using sensory deprivation flotation tanks can experience an increase in peace, serenity, relaxation, happiness, contentment, and/or overall well-being during such usage (Feinstein et al., 2018;Kjellgren et al., 2008;Kjellgren et al., 2001). While there are, of course, differences between perceived OBEs and the environment of a sensory deprivation flotation tank, there are also commonalities in many cases such as the floating sensation in an altered environment. ...
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Phase 1 of the NDE OBE Research Project began on April 13, 2020 and ended on October 15, 2020. Its objective was to (1) identify and define differing types of perceived out-of-body experiences (OBEs), and (2) discover the differences and commonalities among them, focusing on any possible catalysts, the event itself, and the process from beginning to end. This retrospective study was exploratory in nature. This study based the primary categorization of perceived OBEs first on intent as either not self-induced or deliberately self-induced. Not self-induced perceived OBEs were then further subcategorized based on the experient's condition or state, which included physiologically near-death perceived OBEs (NDOBEs), life-danger perceived OBEs (LDOBEs), life-danger-to-near-death perceived OBEs (LD-NDOBEs), and other spontaneous perceived OBEs (OSOBEs). While this study was not able to identify with certainty any specific catalysts for perceived OBEs, it resulted in suggesting a hypothesis that the catalyst for perceived NDOBEs, perceived LDOBEs, and perceived LD-NDOBEs may be an unconscious, adaptive, reactionary process triggered by various psychological and/or physiological stimuli initiating a non-pathological dissociation or detachment. Furthermore, this study found that there were both commonalities and differences among different types and subtypes of perceived OBEs as categorized in this study. One such finding was that most of the features reported in perceived OBEs that took place during real physiological conditions of near-death were also found in some perceived OBEs in which individuals were not actually near death. In particular, this included features such as perceptions of seeing one's own physical body, experiencing a lack of pain, feeling a sense of peace, experiencing different perceptions of time, having a visual life review experience (VLRE), seeing perceived OBE personages, observing a bright light, encountering tunnels, and experiencing a transcendental otherworldly type of environment.
... 16 There are various thermotherapy immersion temperatures (33°C, 35°C, and 37°C), and physiological responses vary proportionally with the increase in water temperature, reaching their maximum after 15 minutes at constant temperature. 15 Warm water leads to muscular relaxation, 17,18 and the aquatic environment also induces a soothing sensation, leading to an analgesic effect via the release of endorphins. 19,20 All these physiological responses are targeted in AT sessions of 50.7 § 12.2 minutes. ...
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Objective Aquatic osteopathy (AO) is a recent discipline that has not yet demonstrated its value compared with existing therapies. This study compared AO with aquatic therapy (AT)—that is, thermoneutral water immersion—using infrared thermography on healthy individuals to assess differences in cutaneous body temperature. Methods Fifty-five healthy individuals were immersed in thermoneutral water for 1 hour and then underwent AO treatment, with application of a classic diagnosis routine and subsequent manual therapy. Thermograms were recorded to measure the distribution of skin surface temperature throughout the entire body after 1 hour of immersion in thermoneutral water (AT) and compared with thermograms taken after AO. Results Visual analysis of the thermograms showed that there were thermographic differences between the 2 groups. A statistical analysis revealed significant differences between post-AT and post-AO thermograms (P = .002): the mean variance in cutaneous body temperature was significantly lower in the post-AO group than in the post-AT group. Therefore, cutaneous body temperatures were more homogeneous after AO than after AT. Conclusion Cutaneous thermal reactions were more homogenous after AO than after AT alone, with cutaneous temperatures returning closer to normal than after AT alone. These reactions may be related to physiological reactions due to a decrease in vasoconstriction or trigger points. Further studies are needed to clarify these physiological reactions to establish the mechanisms of AO and thus better define its indications.
Purpose: The aim of the present investigation was to determine whether a one-hour floatation-REST session could augment recovery from high-intensity resistance exercise (6 x10 back squats, 2 minutes rest) known to induce significant metabolic, adrenergic, and mechanical stress. Methods: Eleven healthy resistance-trained males (age: 22.5 ± 2.3 years; height: 176.4 ± 6.0 cm; weight: 85.7 ± 6.2 kg, back squat 1RM: 153.1 ± 20.1 kg; strength to weight ratio: 1.8 ± 0.2) completed the within-subjects, cross-over controlled study design. Participants completed two exercise testing blocks separated by a two-week washout. In one block, the high-intensity resistance exercise protocol was followed by a one-hour floatation-REST session, while recovery in the alternate block consisted of a passive sensory-stimulating control. Markers of metabolic stress, neuroendocrine signaling, structural damage, inflammation, and perceptions of soreness, mood state and fatigue were assessed over a 48-hour recovery window. Results: Floatation-REST significantly attenuated muscle soreness across recovery (p = 0.035) with greatest treatment difference immediately following the intervention (p = 0.002, ES = 1.3). Significant differences in norepinephrine (p = 0.028, ES = 0.81) and testosterone (p = 0.028, ES = 0.81) immediately following treatment revealed modification of neuroendocrine signaling pathways which were accompanied by greater improvements in mood disturbance (p = 0.029, ES = 0.81) and fatigue (p = 0.001, ES = 1.04). Conclusions: As no adverse effects and significant and meaningful benefits were observed, floatation-REST may prove a valuable intervention for managing soreness and enhancing performance readiness following exercise.
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Introduction: Timely assessment and correction of post-stroke hemiplegia gait, to improve walking ability, has become an urgent problem for patients with hemiplegia. Objective: In order to improve the effect of exercise rehabilitation and tensile strength testing, a three-dimensional gait analysis method was proposed. Methods: The kinematics, dynamics, ground reaction force and surface EMG of lower limbs were measured by VICON (Nexus 1.8.5), a three-dimensional gait analysis system, and Noraxon, a wireless surface EMG, while 13 healthy subjects walked. The intra-group correlation coefficient (ICC) and standard error of measurement (SEM) were used to compare the relative and absolute reliability of the two test results. Results: the re-testability ICC was 78~0.96, the standard error SEM% of kinematics parameters was 4.18~15.6, and the SEM% of dynamic parameters was 3.31~21.82. The SEM% of ground reaction force was 1.70~16.67, and the SEM% of surface EMG signal was 8.00~11.11. Conclusions: 3D gait analysis can improve the effect of exercise rehabilitation and tensile strength testing, and has good retesting reliability. Level of evidence II; Therapeutic studies - investigation of treatment results.
Performed 4 experiments to investigate the effects of different techniques causing noradrenergic and serotonergic depletions in the brain and spinal cord on brief shock-induced analgesia (BSIA). Newborn pups were administered N-2-choloroethyl-N-ethyl-2-bromobenzylamine systemically and 6-hydroxydopamine (6-OHDA) administered either systemically or directly into the locus ceruleus region, or intrathecally into the lumbar subarachnoidal space, caused notable and consistent attenuations of analgesia. Treatments reduced noradrenaline concentrations in the spinal cord drastically. A potentiation of BSIA was caused by the administration of p-chlorophenyl-alanine, whereas administration of 5,7-dihydroxytryptamine, into the nucleus raphe magnus or intrathecally into the subarachnoidal space, produced attenuation of the analgesic effect. Biochemical analyses revealed marked 5-hydroxytryptamine (5-HT) depletions in the spinal cord. Findings are discussed with regard to the role of spinal noradrenaline and 5-HT involvement in BSIA and in reactions to stressful events.
The overall goal of this presentation is to demonstrate the interdisciplinary approach of health professionals and how we are investigating the benefits of using a flotation tank in the treatment of patients with rheumatoid arthritis. Rheumatoid arthritis is one of a large group of diseases in which inflammatory changes and pain are the major features. The effects of these changes on patient mobility and function are so profound that they cause significant changes in the patient’s ability to earn a living, as well as his/her social status.
Three groups of women having premenstrual syndrome (PMS) completed checklists for number and severity of symptoms at prescribed intervals, for the assessment of symptoms over the last eighteen months and symptoms before and subsequent to experimental conditions. They were divided into two experimental float groups and a control group. The two-float group floated in a flotation tank once during a non PMS interval and once during a PMS interval. The one-float group floated only during a non PMS interval. The control group did not float. An analysis of variance using repeated measures revealed several outcomes. There were no significant group differences in overall number or severity of symptoms. When only checklists performed during treatment were assessed, the one-float group showed significantly greater overall symptom severity than the other groups. PMS symptoms vary significantly over all time intervals, and flotation results in immediate reduction of symptoms and severity to very low levels. Subsequent to the onset of PMS symptoms after the non PMS float, symptoms and severity significantly increased beyond what was expected and were significantly decreased only by a second float during the PMS interval. Those who had the second float remained at low levels for both symptom number and severity while the other groups showed significantly higher values.
Nine years ago the first International Conference on Restricted Environmental Stimulation (REST) was held. The mood was one of excitement and anticipation of growth, fueled considerably by the publicity and popularity produced by John Lilly’s creation, the flotation tank. Commercial centers sprouted everywhere as people looked for new ways to feel better, find themselves (and God), and make money. REST researchers who had been around for years were joined by a new generation of researchers and practitioners seduced by the undeniable effects of Flotation REST. Conferences two, three, and four attest to the creativity, industriousness, and tenacity of these people, particularly commendable in view of the scarcity of research funding for their work.
Every year between 33% and 42% of adults experience insomnia (Bixler, Kales, Soldatos, Kales, & Healy, 1979; Mellinger, Balter, & Uhlenhuth, 1985). The inability to get adequate sleep is a symptom that can be either primary or secondary in nature. Seven of nine subclasses are considered secondary. Only two are thought of as primary insomnias; that is, insomnias with no obvious underlying cause, such as a medical or psychiatric condition (Association of Sleep Disorder Centers [ASDC], 1979). The second most common insomnia to be treated is “persistent, psychophysiological insomnia” (Coleman, Roffwarg, & Kennedy et al., 1982).
The purpose of this study was to investigate if experiences induced by flotation-REST (in flotation-tank) are affected by settings or subjects earlier experiences of altered states of consciousness (ASC). No such significant differences were found. Significant effects owing to flotation-REST were found regarding reduction in experienced pain and enhancement of mood. Flotation-REST was considered a pleasurable technique. Different kinds of visual and acoustic effects, altered time perception, and a sense of weightlessness have been reported. Also, deep transpersonal experiences were quite common, and could be distinguished into three types: experiences of one's own childbirth/delivery; feeling of cosmic unity; and experiences of losing contact with the body or out-of-body experiences. Flotation-REST must be regarded as a consciousness-altering method with promising potential for clinical and therapeutic use.
The purpose of this study was to provide information about experiences obtained by illegal drug users and evaluate if these are consistent with Stanislav Grof's expanded model of the human unconscious. Sixteen anonymous former drug users answered a questionnaire about use, experiences, circumstances, and influences of their life. All of them have had some experiences similar to Grof's descriptions. Transpersonal experiences were more reported by those who used to be “heavy” users. Such experiences were also more likely to be reported by those who described themselves as spiritual seekers and by those who made some form of ritual or mental preparation part of their experience. This study also provides general information about Grof's model and some about psychedelic research worldwide.