Accuracy of Fitbit Charge 4, Garmin Vivosmart 4, and WHOOP Versus Polysomnography: Systematic Review
Level 1 - systematic review of randomized trials
Systematic review of diagnostic/validation studies against an objective reference standard (PSG).
OpenAlex W4391456282 · doi:10.2196/52192
What was done
A systematic review following PRISMA guidelines was conducted across PubMed, Web of Science, Google Scholar, Scopus, and Embase to evaluate the accuracy of three consumer wearables (Fitbit Charge 4, Garmin Vivosmart 4, and WHOOP) for measuring sleep parameters and sleep stages. Included studies evaluated commercially available models against polysomnography (PSG) or ambulatory EEG in adult populations. Studies relying on subjective sleep diaries or surveys were excluded.
What was found
From 504 records, 8 studies were included. WHOOP demonstrated the lowest discrepancy relative to reference devices for total sleep time (-1.4 min), light sleep (-9.6 min), and deep sleep (-9.3 min), but the largest discrepancy for REM sleep (21.0 min). Fitbit Charge 4 had the lowest discrepancy for REM sleep (4.0 min) and higher sensitivities for deep sleep (75%) and REM sleep (86.5%) compared to WHOOP and Garmin Vivosmart 4. Garmin Vivosmart 4 and Fitbit Charge 4 both demonstrated moderate overall accuracy against PSG.
Why it matters
Consumer wearables provide accessible, continuous sleep tracking and correlate reasonably well with PSG for aggregate sleep duration, but remain suboptimal for precise sleep-stage architecture analysis.
Limits
The total evidence base is small (8 included studies), and the abstract does not report the total participant sample size, demographics, or exact numerical parameters for Garmin Vivosmart 4. Varied study protocols and rapid hardware/software iteration cycles limit comparability and long-term relevance of specific device findings.
Cited by
- supports Commercial wearable devices are inaccurate at measuring deep sleep and REM sleep stages.