Exploring the acute cardiovascular effects of Floatation-REST

Abstract

The central nervous system (CNS) exerts a strong regulatory influence over the cardiovascular system in response to environmental demands. Floatation-REST (Reduced Environmental Stimulation Therapy) is an intervention that minimizes stimulation from the environment, yet little is known about the autonomic consequences of reducing external sensory input to the CNS. We recently found that Floatation-REST induces a strong anxiolytic effect in anxious patients while paradoxically enhancing their interoceptive awareness for cardiorespiratory sensations. To further investigate the physiologic nature of this anxiolytic effect, the present study measured acute cardiovascular changes during Floatation-REST using wireless and waterproof equipment that allowed for concurrent measurement of heart rate, heart rate variability (HRV), breathing rate, and blood pressure. Using a within-subjects crossover design, 37 clinically anxious participants with high levels of anxiety sensitivity and 20 non-anxious comparison participants were randomly assigned to undergo a 90-min session of either Floatation-REST or an exteroceptive comparison condition that entailed watching a relaxing nature film. Measures of state anxiety and serenity were collected before and after each session, while indices of autonomic activity were measured throughout each session. HRV was calculated using both time-series and frequency domain analyses. Linear mixed-effects modeling revealed a significant main effect of condition such that relative to the film condition, Floatation-REST elicited significant decreases (p < 0.001) in diastolic blood pressure, systolic blood pressure, breathing rate, and certain metrics of HRV including the standard deviation of the interbeat interval (SDNN), low-frequency HRV, and very low-frequency HRV. Heart rate showed a non-significant trend (p = 0.073) toward being lower in the float condition, especially toward the beginning of the session. The only metric that showed a significant increase during Floatation-REST was normalized high-frequency HRV (p < 0.001). The observed physiological changes were consistent across both anxious and non-anxious participants, and there were no significant group by condition interactions. Blood pressure was the only cardiac metric significantly associated with float-related reductions in state anxiety and increases in serenity. These findings suggest that Floatation-REST lowers sympathetic arousal and alters the balance of the autonomic nervous system toward a more parasympathetic state.Clinical trial registration[https://clinicaltrials.gov/show/NCT03051074], identifier [NCT03051074].

Two models of mind blanking

“…In a float tank, external stimuli are minimised to such an extent that individuals often report losing the sense of where their body ends and where the water begins. This experience of reduced sensitivity to bodily perceptual boundaries is illustrated in the work of Flux et al (2022) on Floatation-REST (Reduced Environmental Stimulation Therapy). This involves the practice of reclining in a pool of water that contains an abundance of magnesium sulfate (Epsom salt).…”

A systematic review of Flotation-Restricted Environmental Stimulation Therapy (REST)

“…To explore the mechanism by which flotation-REST induces anxiolytic effects, Flux et al ( 2022) investigated the acute cardiovascular effects of flotation-REST [54]. A total of 57 participants were recruited: 37 participants met the criteria for one or more anxiety disorders and thereby comprised the anxious group, while the remaining 20 participants did not meet the criteria and comprised the non-anxious group.…”

Transdiagnostic failure to adapt interoceptive precision estimates across affective, substance use, and eating disorders: A replication study

“…Future work might explore the utility of Bayesian modeling as a tool for longitudinally assessing interoceptive dysfunctions across various psychiatric disorders. Furthermore, interoceptive training interventions could be developed to target precision-weighting of cardiac signals, potentially offering a novel therapeutic approach for enhancing visceral regulation in affected individuals (see (50)(51)(52)(53)(54) for examples of some candidate approaches impacting the cardiac domain). These interventions may be especially pertinent for patient populations demonstrating significant interoceptive deficits, such as those with anxiety, substance use, and eating disorders, and could provide an initial framework for developing targeted therapeutic strategies.…”