Date Presented 4/17/2015
This study tested the effects of deep pressure, applied through an inflatable vest, on autonomic arousal in typical adults. Results indicate that deep pressure can reduce sympathetic arousal and can increase parasympathetic arousal and may be useful with diagnostic groups that exhibit overarousal or anxiety.
SIGNIFICANCE: This study tests a foundational principle guiding sensory integration intervention, which is that deep pressure is beneficial due to its effect on the autonomic nervous system. Findings from this study can be used to support current clinical practice and future clinical trials.
INNOVATION: This study is innovative in its use of objective physiological measurements for assessing the effects of deep pressure input.
RESEARCH QUESTION: What are the effects of deep pressure stimulation on measures of autonomic arousal and performance?
BACKGROUND RATIONALE: Deep pressure has been used in clinical practice on the basis of the assumption that it changes arousal. Unfortunately, evidence for use of deep pressure is severely limited, and that which does exist includes inconsistent application without objective measures. This study tested the effects of deep pressure, applied via a Vayu Vest (Food and Drug Administration [FDA] Class-1 exempt product), on autonomic arousal and performance in typical adults. We hypothesized that deep pressure will (1) decrease sympathetic arousal, (2) increase parasympathetic activation, and (3) improve cognitive performance.
METHOD: The study used a repeated-measures, repeated-baseline design. The setting was a public research university laboratory. Participants included 50 adults (μ age = 24.5 yr; M = 13, F = 34, unreported = 3) with no significant sensory, motor, or cognitive disorders. Autonomic data were collected with the Mindware system; electrodes were placed on the participants’ chest, back, and palm to collect data relative to changes in skin conductance level (SCL), number of nonspecific responses (NSRs), and respiratory sinus arrhythmia (RSA). Performance was measured with a brain teaser game, The Moron Test, played on an iPod Touch®.
Subjects were randomly assigned to one of six versions to play at Test 1 and Test 2. The outcome of interest was the number of total errors per test epoch. Data were collected during seven 3-min epochs: Baseline 1, Moron Test 1, Baseline 2, Vayu Vest, Baseline 3, Moron Test 2, and Recovery. Data were analyzed using repeated-measures analysis of variance (ANOVA); gender was used as a covariate.
RESULTS: Changes in SCL during the Vayu epoch showed a significantly greater decrease than all other epochs except for final recovery (p < .05). Total NSRs was also significantly less during the Vayu epoch compared to all other epochs (p < .01). RSA during the Vayu epoch was significantly greater than during all other epochs except for Baseline 1 (p < .05). Participants made significantly (p < .01) fewer errors on the Moron Test after wearing the Vayu Vest.
CONCLUSION: All hypotheses were supported, suggesting that wearing the Vayu Vest for short periods of time reduces sympathetic arousal and nonstimulus driven electrical occurrences (NSRs; an index of arousal). Concomitantly, increases in parasympathetic activation were noted leading to an overall autonomic response that is calming to subjects. Although the Moron Test is unstandardized, it provides a proxy for a more standardized attention measure. Findings indicate that performance is significantly improved after wearing the Vayu Vest, potentially due to noted changes in arousal. We conclude that deep pressure can elicit changes in autonomic arousal and may be useful with diagnostic groups that exhibit overarousal, anxiety, or stress-related behaviors.
