Heart rate and CVHR
What cyclic variation of heart rate tells you about your night.
Updated 2026-06-28
Beyond average heart rate, Wellue Sync surfaces CVHR — cyclic variation of heart rate — a pattern of rhythmic accelerations and decelerations that often tracks with disturbed breathing.
The heart-rate metrics
- Mean / min / max heart rate across the night.
- Std dev — overall variability of your beat-to-beat rate.
- CVHR — the strength of the cyclic rise-and-fall pattern. Elevated CVHR can accompany repeated arousals.
- HR-to-SpO₂ coupling — how tightly heart-rate swings line up with oxygen dips.
A high CVHR paired with a high ODI is the classic autonomic signature of fragmented sleep. Tracking both over time shows whether a change you made is actually helping.
Compare these numbers across nights with session comparison.