Body Versus Machine: Deep Breathing Versus Vagus Stimulation for the Treatment of Fibromyalgia

The primary objective of this randomized controlled trial is to investigate the effects of motivational nondirective resonance breathing (MNRB) and transcutaneous vagus nerve stimulation (tVNS) on autonomic health and pain intensity in participants diagnosed with chronic widespread pain (CWP). Two versions of MNRB and two versions of tVNS will be delivered and practiced by participants at home for two weeks. The primary outcome is photoplethysmography (PPG) measured heart rate variability (HRV). Secondary outcomes are self report numeric rating scale (NRS) pain intensity, FM pain severity and associated parameters, computerized cuff pressure algometry, blood pressure, psychological distress and health related quality of life.