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

Abstract

Reduced Environmental Stimulation Therapy (REST) alters the balance of sensory input to the nervous system by systematically attenuating sensory signals from visual, auditory, thermal, tactile, vestibular, and proprioceptive channels. Previous research from our group has shown that REST via floatation acutely reduces anxiety and blood pressure (BP) while simultaneously heightening interoceptive awareness in clinically anxious populations. Anorexia nervosa (AN) is an eating disorder characterized by elevated anxiety, distorted body representation, and abnormal interoception, raising the question of whether REST might positively impact these symptoms. However, this approach has never been studied in eating disorders, and it is unknown whether exposure to floatation REST might worsen AN symptoms. To examine these possibilities, we conducted an open-label study to investigate the safety and tolerability of REST in AN. We also explored the acute impact of REST on BP, affective symptoms, body image disturbance, and interoception. Twenty-one partially weight-restored AN outpatients completed a protocol involving four sequential sessions of REST: reclining in a zero-gravity chair, floating in an open pool, and two sessions of floating in an enclosed pool. All sessions were 90 min, approximately 1 week apart. We measured orthostatic BP before and immediately after each session (primary outcome), in addition to collecting BP readings every 10 min during the session using a wireless waterproof system as a secondary outcome measure. Each participant’s affective state, awareness of interoceptive sensations, and body image were assessed before and after every session (exploratory outcomes). There was no evidence of orthostatic hypotension following floating, and no adverse events (primary outcome). Secondary analyses revealed that REST induced statistically significant reductions in BP ( p < 0.001; Cohen’s d , 0.2–0.5), anxiety ( p < 0.001; Cohen’s d , >1) and negative affect ( p < 0.01; Cohen’s d , >0.5), heightened awareness of cardiorespiratory ( p < 0.01; Cohen’s d , 0.2–0.5) but not gastrointestinal sensations, and reduced body image dissatisfaction ( p < 0.001; Cohen’s d , >0.5). The findings from this initial trial suggest that individuals with AN can safely tolerate the physical effects of REST via floatation. Future randomized controlled trials will need to investigate whether these initial observations of improved anxiety, interoception, and body image disturbance occur in acutely ill AN populations. Clinical Trial Registration ClinicalTrials.gov ; Identifier: NCT02801084 (April 01, 2016).

Flotation Restricted Environmental Stimulation Therapy for Chronic Pain

“…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, lowered stress levels, improved sleep quality, reduced anxiety, and pain relief …”

Exploring the acute cardiovascular effects of Floatation-REST

“…Specifically related to cardiovascular changes that occur as the result of Floatation-REST, several studies have reported significant reductions in both systolic and diastolic blood pressure when comparing measurements taken before and after a float session (Jacobs et al, 1984;Turner et al, 1989). More recently, our lab has found significant blood pressure reductions during the actual float session, with diastolic blood pressure showing the largest decrease when compared to watching a nature documentary (Feinstein et al, 2018b) or lying supine in a zero-gravity chair (Khalsa et al, 2020). Two previous studies explored the effects of Floatation-REST on heart rate (Forgays and Belinson, 1986;O'Leary and Heilbronner, 1990) with variable results.…”

“…This window into ANS functioning in the absence of sensory stimulation could provide a novel paradigm for measuring an 10.3389/fnins.2022.995594 individual's true physiologic baseline, one that is untethered from the influences of the external world. However, the baseline state engendered by floating is not affectively neutral, as prior research has shown that the float experience induces a state of serenity and decreased anxiety, effects that were most pronounced in clinically anxious patients (Feinstein et al, 2018a,b;Khalsa et al, 2020). Notably, all of the patients had high levels of anxiety sensitivity, which refers to one's fear of experiencing anxiety-related symptoms and sensations, especially those arising from within the body (Taylor, 2014).…”

“…Notably, all of the patients had high levels of anxiety sensitivity, which refers to one's fear of experiencing anxiety-related symptoms and sensations, especially those arising from within the body (Taylor, 2014). Interestingly, the float environment was found to enhance awareness for interoceptive sensation, especially sensations emanating from the cardiorespiratory system (Feinstein et al, 2018b;Khalsa et al, 2020). This presents a paradox, as one might expect individuals with high anxiety sensitivity to find the conscious experience of cardiorespiratory sensations to be anxiety inducing (rather than reducing).…”