Date of Award

Summer 2019

Document Type

Open Access Thesis


Epidemiology and Biostatistics

First Advisor

James Burch


Healthy amounts of sleep is vital for normal human functions such as daily learning, memory, emotional state and cardiovascular function. Studies conducted previously have shown sleep deprivation to be associated with increases in sympathetic activity contributing to autonomic nervous system (ANS) dysregulation. HRV biofeedback (HRVB) training induces HRV coherence, a condition that maximizes HRV and facilitates autonomic and cardiorespiratory homeostasis. This randomized, controlled, intervention trial will test the hypothesis that HRVB can improve HRV coherence and increase overall sleep quality. Patients are randomized to previously established HRVB or sham protocols (n=40 each, total planned enrollment N=80). Each participant completes a baseline assessment, 6 weekly training sessions, a post-training assessment, a booster training session and assessment (1-month post-training), and a follow-up assessment (2 months post-training). Wrist actigraphy is used to obtain continuous rest/activity recordings 24-hours per day over three 1-week periods coinciding with the baseline, post-treatment, and follow-up assessments. Subjective sleep symptoms are included at each assessment using the Pittsburg Sleep Quality Index (PSQI). Outcomes include: 15-minute resting HRV recordings (HRV Coherence Ratio), as well as subjective (total PSQI and sleep quality scores) and quantitative sleep measures (actigraphic sleep onset latency, duration, efficiency, wake after sleep onset). To date, 85 patients completed their baseline assessment; 63 completed their post-training assessment, and 50 completed the entire protocol. In preliminary analyses, HRVB patients had elevated mean (±SD) HRV Coherence Ratios at the post-training assessment relative to baseline (0.11±.02 vs. 0.27±0.05, n=43, p<0.001), whereas no differences were observed among controls (0.10±0.02 vs. 0.12±0.02, n=41, p=0.97). Compared to baseline scores PSQI Global Score was reduced at Post Assessment (12.3±0.5 vs 11.1±0.6 n=31, p=0.02) and at Follow-up Assessment (12.3±0.5 vs 10.3±0.9 n=25, p<0.001); no differences among controls. Compared to baseline scores Sleep Duration elevated at Post Assessment (436±15 vs 465±19 n=23, p=0.03) and at Follow-up Assessment (436±15 vs 479±19 n=21, p=0.02); no differences among controls. Preliminary results indicate receipt and persistence of intervention among HRVB participants to date. Results show evidence of Subjective (PSQI) and Objective (Duration) sleep improvements. HRVB is a valid, quantifiable, easily-implemented procedure; and previous research suggests that HRVB can improve overall sleep quality.


© 2019, Joshua Mercadel

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