Summary
| Direction in ME/CFS | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Autonomic |
| Also described as | Parasympathetic tone |
| Compared against | HC (healthy controls) |
| Associated symptoms | Dysautonomia, orthostatic intolerance |
| Test type | Clinical or physiological test |
| Source | Nelson et al. 2019 — doi:10.1186/s12967-019-02100-4 |
| Condition atlas | ME/CFS Biomarker Atlas |
Other conditions where Heart rate variability (HRV) is reported
- Heart rate variability (HRV) in Gulf War Illness — ↓ reduced vs HGV
- Heart rate variability (PTLDS) in Lyme Disease — ↓ reduced vs HC
- Heart rate variability (SDNN) in ME/CFS — ↓ reduced vs HC
- Heart rate variability (HRV) in PACVS — ↓ reduced vs HC
See the cross-condition hub: Heart rate variability (HRV) across conditions.
Related Autonomic markers in ME/CFS
- Heart rate variability (SDNN) ↓
- LF/HF ratio ↕
- Orthostatic heart rate increment ↑
- Blood pressure variability ↑
- Baroreflex sensitivity ↓
Full list: ME/CFS Biomarker Atlas.
Frequently asked questions
Is Heart rate variability (RMSSD) high or low in ME/CFS?
Reduced. Studies summarised in the OSMF atlas report lower Heart rate variability (RMSSD) in ME/CFS than in healthy controls. Source: Nelson et al. 2019.
What symptoms is Heart rate variability (RMSSD) associated with in ME/CFS?
The cited literature associates this marker with Dysautonomia, orthostatic intolerance. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Heart rate variability (RMSSD)?
It is measured as a clinical or physiological test. Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal Heart rate variability (RMSSD) result diagnostic of ME/CFS?
No. No single biomarker is diagnostic of ME/CFS. Heart rate variability (RMSSD) findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is Heart rate variability (RMSSD) specific to ME/CFS?
No. The same marker is also reported in Gulf War Illness, Lyme Disease, ME/CFS, PACVS in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
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Last reviewed: 2026-06-29 · Page generated from me-cfs.json · Browse: ME/CFS atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.