IntroductionMeditation offers a tractable model for probing altered states of consciousness, yet consistent physiological markers remain elusive. This study characterized within-subject autonomic and respiratory modulation across pre-meditation, during-meditation, and post-meditation states in trained Rajyoga practitioners using multiscale heart rate variability (HRV) metrics and HRV–respiration coupling. Sex-stratified analyses were presented exploratorily to summarize state-dependent effects.M