Brief online mindfulness meditation training modulates heart rate variability during post-stress meditation

Mindfulness-based interventions are increasingly delivered online, yet evidence for short programs often relies on self-report outcomes. We tested whether a brief online mindfulness meditation training produces detectable changes in autonomic regulation during a standardized stress-to-meditation sequence. Healthy adults with no meditation experience were randomized to a four-week online mindfulness meditation program (MG) or an active health-management program (CG). Before and after training, participants completed a laboratory session consisting of rest, a mental arithmetic stress task, guided focused-attention breathing meditation, and post-rest while ECG was recorded. Across the training period, both groups showed reduced negative affective symptoms, but only the mindfulness group showed an increase in the Observing facet. Critically, frequency-domain HRV indices during the laboratory protocol showed a group-specific post-training pattern: MG exhibited lower LF/HF and higher normalized HF power (nHF) compared with pre-training, and MG differed from CG in the post-training session. Within MG, training-related improvement in FFMQ Non-reactivity was positively associated with nHF during the post-stress meditation period. These findings indicate that a brief online mindfulness program can modulate HRV during a stress-to-meditation context and that post-stress autonomic modulation during meditation covaries with acceptance-related skill acquisition.