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Reduced Environmental Stimulation in Anorexia Nervosa

Summary of Research Paper

Reduced Environmental Stimulation in Anorexia Nervosa: An Early-Phase Clinical Trial

Sahib S. Khalsa et al. Published 6th Oct 2020


  • The purpose of the study was to explore the safety of Floatation Therapy for users suffering with AN triggered Orthostatic Hypotension, and impact of Floatation Therapy on conditions associated with Anorexia Nervosa (AN) which include, but are not limited to Anxiety, Personality Disorders and Mood Disturbances.

  • It is also noted that existing ‘go to ‘ treatments for these mental health issues show little to no efficacy in treating these conditions when associated with AN.

  • Following previous published studies relating to Floatation Therapy being used to treat Anxiety and other mood disorders, it was pondered whether REST via Floatation might positively impact affective and interoceptive symptoms in individuals with AN such as raised Respiratory and Cardiac Rate, increased muscle tension and emotional instability, especially where Food or related triggers are involved.


  • With no previous study indicating a level of safety or tolerability using Floatation with participants suffering from AN, an initial open study was conducted with 50 individuals with diagnoses of Anxiety and mood related disorders. Following recruitment, the participants undertook a single 1hr session and following diagnostic questioning reported as being ‘well tolerated’ by the anxious sample, with no major safety concerns or adverse events which would prevent the study from proceeding. It was noted that ‘regardless of diagnosis, the float experience induced a strong short-term reduction in state anxiety and a substantial improvement in mood’.

  • A follow up study was then conducted where a further 31 individuals with diagnosed anxiety and mood related disorders were evaluated during a 90 min Floatation session with a ‘control/comparison’ made by the same participants watching a ‘relaxing’ film. Measures of self-reported affect and interoceptive awareness were collected before and after each session, and BP was measured during each session.

  • Before engaging participants with AN, it was hypothesised that the increase in perception of the physical state and the reduction of Cardiac and Resp rates may worsen the effect of AN both physically and mentally. However, with no evidence to reference it was decided to recruit the initial participants with weight recovered AN and decided upon Orthostatic Hypotension as the ‘safety measure’. Orthostatic Hypotension could increase fall and/or a risk of feinting when transitioning from laying to standing (an action occurring at the end of each float) (Sachs et al., 2016.) This measure was chosen as Orthostatic Hypotension is a major medical condition associated with acute dehydration that is especially common in underweight and even partially weight-restored AN patients (Lanier et al., 2011).

Aim and Methodology

  • The primary objective of this study was to determine whether individuals with partially weight-restored AN would exhibit evidence of orthostatic hypotension following REST, inhibiting the use of REST for this purpose. If the risk was not shown, then the secondary objective of this study was to examine the acute effects of REST on BP during floating and subjective measures of emotional experience (including anxiety and mood), body image disturbance, and interception. These secondary aims were exploratory and intended to provide information on the subjective changes induced by REST in individuals with AN, assisting in the dentification of potentially useful targets for future studies.

  • Participants exposed to four treatments, approx. 1 week apart.

    • Session 1 was undertaken in a ‘zero gravity’ chair

    • Session 2 was undertaken in an open Float Pool to acclimatise to the sensation of Floating

    • Sessions 3 & 4 undertaken in an enclosed Float Pool.

    • All sessions were set for 90mins with the participant able to end their session at any point.

Outcome Measurements

  • Blood Pressure Measurements - During each session, orthostatic BP was measured before and after each float.

  • Multiple Diagnostic Questionnaires used to record perceived effects ranging from psychological effect on mood, anxiety levels etc, physical effects such as muscle tension and specialist diagnostic papers relating specifically to AN.

  • Post Session Interviews were conducted by the researcher to assess the participant experience and record information provided.


Primary Outcome of Orthostatic Hypotension measurement

  • None of the participants completing any float session exhibited evidence of meeting the established criteria for Orthostatic Hypotension. With respect to other safety measures, no falls were observed upon standing, and there were no reports of feeling lightheaded or dizzy. Additionally, there were no adverse events such as acute panic attacks, severe dysphoria, agitation, or increased suicidal ideation.

Secondary Outcomes –

  • With regard to blood pressure, the session undertaken in the Chair showed a slight increase in Systolic bp when compared to baseline and Pool Floatation showed a measurable decrease (with the lowest levels being recorded between the 25th and 65th minutes of the 90 min session) and the greatest decrease in the final session, although none of the changes were regarded as substantial. Diastolic BP showed a more consistent decrease across both sessions of floatation-REST as compared with chair-REST and a slight reduction from baseline.

Psychological Diagnostic questionnaire results returned the following –

  • Interoceptive Awareness Measures – during REST, participants reported feeling significant increases in the intensity of the sensations from their heartbeat and breath but not from their stomach/digestive system.

  • Body Appreciation - analysis of variance comparing the post-float assessments vs. the initial baseline assessment did not observe a statistically significant difference across sessions.

  • Body Image States Scale & Photographic Figure Rating Scale – in contrast to body appreciation, participants reported significantly reduced body image dissatisfaction from pre- to post-REST & across all four REST sessions, suggesting a statistically significant increase in more favourable body image state and impacting personal appreciation when comparing personal impression to that of a photographic image of themselves.

  • Effect Sizes for Secondary and Exploratory Outcome Measures - REST elicited moderate (0.5) to large (0.8 and greater) effects on ratings of state anxiety, stress, refreshment, serenity, relaxation, energy, and PFRS body dissatisfaction. REST elicited small (0.2) to moderate (0.5) effects on BP, heartbeat and breath intensity, and negative attitudinal body image. REST appeared to have minimal effects on stomach/gastrointestinal sensation intensity ratings and positive body appreciation ratings.

  • Post session Interviews - Overall, most participants found the REST experience to be positive.


  • Overall, the findings from this initial trial suggest that individuals with partially weight-restored AN can safely tolerate the physical effects of REST.

  • They may also experience improvements in anxiety and body image disturbance, but further studies involving randomized controlled designs would be required to confirm this finding.

Marketing Take Away

  • The primary aim of the study was to investigate the safety and tolerability of REST in AN.

  • There were no indications that Floatation therapy should be avoided by patients with Cardiovascular interference due to AN.

  • The Secondary aim was to explore the impact of REST on affective symptoms, body image disturbance, and interception relating to AN. The study shows…

  • Significant reductions in several affective measures from pre- to post-float, including self-reported state/levels of anxiety, stress and fatigue.

  • It was also reported that there was a significantly positive affect on levels of relaxation, joviality, a feeling of refreshment, increased energy, and serenity.

  • These results are potentially noteworthy for several reasons and the study states that

    1. current anxiolytic medications such as benzodiazepines (Steinglass et al., 2014) and behavioural treatments for anxiety in AN show limited efficacy and Floatation Therapy could be used as an alternative treatment path.

    2. the magnitude of the effect of Floatation Therapy was large.

    3. they mirror our previous observations of acute anxiety reductions in transdiagnostic groups of individuals with heightened anxiety sensitivity (Feinstein et al., 2018a).

It is important to emphasize that such observations are to be regarded as preliminary until they can be verified in subsequent studies employing control conditions and randomized participant assignment, to account for the potential impact of expectancies on responses to this novel behavioural intervention.” J Feinstein.

  • Floatation-REST generated a significant anxiolytic (anti-anxiety) effect relative to the comparison condition that was characterized by reductions in perceived anxiety and muscle tension, alongside increases in feelings of relaxation and serenity.

  • In addition, significant BP reductions were evident throughout the float sessions.

  • It was also reported that these individuals were left with a perceived increase in perception of these measures, primarily the respiratory and Cardiac rates.

Summarization of -

Reduced Environmental Stimulation in Anorexia Nervosa: An Early-Phase Clinical Trial

Sahib S. Khalsa, Scott E. Moseman, Hung-Wen Yeh, Valerie Upshaw, Beth Persac, Eric Breese, Rachel C. Lapidus, Sheridan Chappelle, Martin P. Paulus and Justin S. Feinstein

Laureate Institute for Brain Research (LIBR), Tulsa, OK, United States, Oxley College of Health Sciences, The University of Tulsa, Tulsa, OK, United States, Laureate Eating Disorders Program, Tulsa, OK, United States, Children’s Mercy Health System, Kansas City, MO, United States, Department of Psychology, The University of Tulsa, Tulsa, OK, United States.

Summarized by - N. Parsons 21/09/2021

Download the full paper below

Anorexia Nervosa 2020
Download PDF • 1.91MB

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