The efficacy of heart rate variability biofeedback training on sleep disorders and impact of fibromyalgia: Results of a phase II randomized controlled trial

Objective: Fibromyalgia syndrome (FMs) is a chronic, musculoskeletal pain disorder characterized by sleep disturbances, fatigue, and cognitive dysfunction. Heart rate variability biofeedback (HRV-BF) aiming to improve self-regulation and strengthen the parasympathetic nervous system has been shown to be effective in several pain syndromes, but its efficacy in FMs has not been adequately investigated. This Phase II trial aimed to assess the feasibility and preliminary measurement of the improvement induced by HRV-BF in FMs. Methods: Sixty-four patients with FMs were recruited. Patients were randomly assigned to either the experimental group (EG) or the control group (CG). The EG received 10 HRV-BF training sessions in addition to pharmacological standard therapy. The CG received standard therapies for 10 weeks. The FMs impact on daily life, sleep regularity, sense of coherence, depression symptoms and pain has been assessed as primary outcomes, quality of life as secondary. Result: 23 (71.9%) of EG patients completed the intervention and 20 (62.5%) of the CG were re-evaluated at time T1. No side effects were reported. It was not found any statistical differences between groups over time in primary and secondary outcomes. Conclusions: The HRV-BF intervention did not demonstrate efficacy in both primary and secondary outcomes. However, it is quite feasible in terms of drop-out rate and side effects. Further studies with larger sample sizes are needed to determine its actual efficacy. Clinicaltrials: gov with code: NCT04121832.