Effects of an Integrated Yoga and Yoga Nidra Intervention on Heart Rate Variability and Autonomic Function in School-Aged Children: An Experimental Study

Background: Heart rate variability (HRV) is a reliable, non-invasive biomarker of cardiac autonomic regulation. While evidence supports yogic practices in modulating autonomic function in adults, pediatric research remains limited. Objective: This study investigated the acute effects of an integrated yogic intervention—comprising Bhramari Pranayama, Adi Mudra, Navasana, and Yoga Nidra—on 16 comprehensive HRV metrics in school-aged children (ages 8–12 years). Methods: 82 students from Auroville, Tamil Nadu, India were randomly allocated into intervention (n = 41) and control (n = 41) groups. HRV was continuously recorded across three phases: Pre (3 min), During Yoga Nidra (20 min), and Post (3 min). The same 41 responders were identified by LF/HF ratio reduction. Sixteen HRV metrics were analyzed using repeated measures ANOVA with Bonferroni-corrected pairwise comparisons. Results: Significant omnibus effects were observed for RMSSD (F = 3.38, p = .037, η² = .053), PNS Index (F = 3.18, p = .045, η² = .050), SNS Index (F = 4.03, p = .020, η² = .063), Stress Index (F = 3.98, p = .021, η² = .062), and SD1 (F = 3.33, p = .039, η² = .053). Pre-to-Post comparisons revealed significant enhancements in parasympathetic markers (RMSSD: d = −0.44; PNS Index: d = −0.42; pNN50: d = −0.51) and significant reductions in sympathetic markers (SNS Index: d = 0.52; Stress Index: d = 0.53). Conclusion: The integrated yogic intervention produced statistically significant and clinically meaningful shifts toward parasympathetic dominance in school-aged children.