Yoga Nidra for cardiovascular health: a systematic review and meta-analysis of between- and within-group effects

Abstract

Introduction: Cardiovascular diseases remain a leading cause of morbidity and mortality worldwide, with hypertension being a major risk factor. Yoga Nidra (YGN), a guided meditative practice focused on relaxation, has gained attention for its potential cardiovascular effects. Despite this, a clear understanding of YGN's efficacy remains limited. This systematic review and meta-analysis assessed the effects of YGN on various cardiovascular parameters.

Methods: A comprehensive literature search was conducted across seven academic databases including PubMed, PsycINFO, CINAHL, SPORTDiscus, Scopus, Web of Science, and ProQuest, as well as one trial database, the Cochrane Central Register of Controlled Trials. The methodological quality of the included studies was assessed using the Cochrane Risk of Bias 2 tool for randomized trials and the Downs and Black checklist for non-randomized studies.

Results: A comprehensive literature search across seven databases identified 620 articles, of which 28 met the inclusion criteria for analysis. The quality assessment revealed that most included studies had methodological limitations. The between-group meta-analysis demonstrated significant small-to-large effect improvements in systolic blood pressure (Hedges' g: -1.65), diastolic blood pressure (-1.01), heart rate (-0.73), and heart rate variability parameters such as low to high frequency ratio (-0.35), when YGN was compared to active control groups. These findings were supported by within-group analyses and leave-one-out sensitivity tests.

Conclusion: The results indicate that YGN practice was associated with improvements in cardiovascular health markers across the analyzed studies. However, the methodological limitations identified in the current literature indicates that high-quality, rigorously designed randomized controlled trials are needed to strengthen the evidence base for YGN's effectiveness in reducing the risk of cardiovascular diseases.

Keywords: Blood pressure; Hypertension; Meditation; Relaxation; Yoga; Yoga Nidra.