A Systematic Review of the Effects of Bhramari Pranayama on the Central and Autonomic Nervous System

Abstract

This systematic review is an investigation into the effects of Bhramari pranayama (Bhramari), a yogic breathing practice, and its effects on the central and autonomic nervous systems. To be eligible for inclusion a study must have reported using a variant of Bhramari, which at minimum must have included nasal breathing and humming, any studies combining these two aspects but not defining them as Bhramari were also eligible. Further, the studies must have included one or more markers or tests of autonomic nervous system activity, central nervous system activity, and/or cognitive function. Studies with treatment groups combining Bhramari with other interventions were excluded. ScienceDirect, Scopus, Web of Science, ClinicalKey, EBSCO Health Databases and MEDLINE were last searched on the 8th of December using the term “Bhramari” and eighteen studies were deemed fit for inclusion. The first author extracted results from the included studies into extensive excel tables, which were then summarized to create summary tables, and a risk of bias assessment using the Cochrane risk-of-bias tool for randomized trials (RoB 2). The studies reviewed revealed a modest but consistent, shift to parasympathetic dominance in ANS metrics, increase in paroxysmal gamma waves and alteration of wave power and expression in EEG reading, and increased concentration and accuracy in cognitive assessments. This was present over the domains of autonomic functioning, central nervous system function and cognitive testing. However, the risk of bias assessment resulted in a high risk of bias result for the majority of studies assessed. This is reflective of the large heterogeneity of studies reviewed with heterogeneity being present as far as Bhramari implementation. Therefore, further research should focus on verifying existing findings with more rigorous publications along with methods designed to better deduce mechanism of effect.