Abstract
Markil and colleagues report increased heart-rate variability after yoga nidra — consistent with parasympathetic shift — whether or not hatha yoga preceded the session.
Markil, N., Whitehurst, M., Jacobs, P. L., & Zoeller, R. F. (2012). Alternative Therapies in Health and Medicine, 18(2), 44–50. DOI
Key findings
- HRV rise — Yoga nidra produced higher HRV versus pre-session baseline in this crossover design.
- Asana-independent — Prior hatha yoga did not block the HRV response to nidra.
- Autonomic readout — HRV used as parasympathetic balance proxy — not a full sleep substitute endpoint.
- Single-session design — Acute effect only — long-run training effects not tested here.
Limits
Small sample · alternative medicine journal — replication with polysomnography and larger N still needed.
Application
One honest down-regulation rep — measure subjective calm or HRV if you track it; see Down-Regulation · Non-Sleep Deep Rest (NSDR).