Validation of nocturnal resting heart rate and heart rate variability in consumer wearables
Dial MB · Hollander ME · Vatne EA · Emerson AM · Edwards NA · Hagen JA
Physiological Reports · 2025
What the research tells us
Five wearables showed differing agreement with a chest-strap ECG reference for nocturnal HRV. Reported concordance correlation coefficients were .87 for Garmin, .97 for Oura 3, .99 for Oura 4, .82 for Polar and .94 for WHOOP. This assesses basic nocturnal measures, not manufacturers' composite recovery scores.
Scope & interpretation
Sampling windows and algorithms differ, and nights are repeated within people. Table 3 reports Polar bias of −4.65 ms but limits of −14.30 to 23.60 ms, whose midpoint is +4.65 ms. The original PDF shows the same values; difference direction remains unresolved, so these limits should not define a precise device threshold.
Study at a glance
- POPULATION & SAMPLE
- 13 healthy adults contributing 536 nights; valid nights differed by device and are not independent participant counts.
- EXPOSURE / INTERVENTION / SUBJECT
- Garmin, Oura 3/4, Polar and WHOOP compared with Polar H10 single-lead ECG processed in Kubios, allowing less than 5% corrected beats in the reference.
- OUTCOMES
- Agreement, mean bias and limits of agreement for nocturnal resting heart rate and HRV.
- TIME FRAME
- Repeated nights, with device-specific valid counts of 150, 470, 139, 206 and 289.
Editorial & review record
Record for v1.0 · Updated
Editorial responsibility: TAP Editorial Team
Scientific review
Not yet scientifically reviewed
Editorial note
Under the editorial responsibility of the TAP Editorial Team, this publication used AI assistance for content organization and editing. Scientific review is recorded separately on this page.
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How responsibilities and review are recorded ↗Scope of this reading note
Full-text participants, processing, statistics, Table 3 and limitations, including visual comparison with the original PDF. Within-person agreement and difference direction require further checking.
- Study funding
- US Air Force Research Laboratory, award S-194-11T-001.
- Competing interests
- The authors declare no competing interests.
Project support
Founded and supported by Resilio.
Revision history
- · v1.0
Added nocturnal device-agreement evidence, the 13-person repeated design and the unresolved Polar table issue.