Author Type

Graduate Student

Date of Award

Fall 11-7-2025

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

November 2025

Department

Counselor Education

Degree Name

Doctor of Philosophy (PhD)

Thesis/Dissertation Advisor [Chair]

Kelly Emelianchik-Key

Abstract

Posttraumatic Stress Disorder (PTSD) affects approximately 5 to 8 percent of the U.S. population annually, contributing to significant healthcare costs and high psychotherapy dropout rates (Kessler et al., 2005; Kilpatrick et al., 2013; National Center for PTSD, 2023a). Understanding the factors that contribute to treatment attrition and identifying effective interventions that promote safety, engagement, and sustained participation in therapy are critical priorities in trauma counseling.

This study examined the impact of a polyvagal theory-informed intervention, the Safe and Sound Protocol (SSP), on trauma symptoms, autonomic reactivity, and the quality of the therapeutic relationship in adult clients diagnosed with trauma- and stressor-related disorders. The SSP is a non-invasive acoustic vagal nerve stimulation intervention designed to regulate the autonomic nervous system and support a neurophysiological state of safety (Unyte Health, 2023a). A single-case research design was utilized to evaluate outcomes across a baseline, intervention and maintenance phase. Standardized measures of trauma symptomology, autonomic nervous system functioning, and therapeutic engagement were administered at multiple time points to assess change over time. Visual analysis and Tau-U effect size calculations indicated clinically meaningful improvements in trauma symptom reduction and autonomic regulation during and after the intervention. SSP did not appear to impact the quality of the therapeutic relationship.

Findings from this study provide preliminary evidence that polyvagal-informed interventions such as the SSP may reduce trauma symptoms, improve autonomic regulation, and enhance treatment retention. By supporting clients in achieving a regulated physiological state, the SSP may serve as a valuable adjunct to trauma counseling, mitigating dropout risk and promoting sustainable therapeutic change.

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