Study record · meta analysis · 2025

Performance of consumer wrist-worn sleep tracking devices compared to polysomnography: a meta-analysis

Lee YJ, Lee JY, Cho JH, and Choi JH

Journal of Clinical Sleep Medicine · 2025

Why this study matters to CircaTest

The most comprehensive recent meta-analysis of consumer wrist-worn sleep trackers vs PSG: 24 studies, 798 patients, 12 different brands including Fitbit, WHOOP, Garmin, Apple Watch, Empatica E4, and Xiaomi Mi Band 5. Headline finding is that across the entire device set, consumer wrist trackers UNDERESTIMATE total sleep time by ~17 minutes (95% CI -26 to -7) and UNDERESTIMATE sleep efficiency by ~4.7 percentage points, both statistically significant. This is the strongest published quantitative answer to the question 'how wrong are consumer trackers on average' across the wrist-worn category. Important limit: pooled across brands, no per-device breakdown extracted into this record.

Abstract

STUDY OBJECTIVES: The use of sleep tracking devices is increasing as people become more aware of the importance of sleep and interested in monitoring their patterns.…

Read the full abstract on the source →

Source: PUBMED · Excerpt for fair-use commentary; full abstract via the source link

Population

Sample size

n = 798

Age

varies across included studies

Reference standard

psg

Meta-analysis pooling 24 individual studies covering 798 participants total. Devices included Fitbit, Jawbone, myCadian, WHOOP, Garmin, Basis B1, Zulu, Huami Arc, Empatica E4, Fatigue Science Readiband, Apple Watch, and Xiaomi Mi Band 5. Searched up to March 2024.

Devices and metrics

Apple Watch (multiple generations across included studies)

All studies for this device →

Metric	Value	95% CI	Note
Bias (minutes)	-16.85 min	-26.33–-7.38	Pooled mean difference for total sleep time across ALL devices in the meta-analysis (not Apple Watch specific). Statistically significant underestimation. Per-device breakdown is in the full paper, not the abstract.

Fitbit (multiple models across included studies)

All studies for this device →

Metric	Value	95% CI	Note
Sleep efficiency	-4.69%	-7.08–-2.3%	Pooled mean difference for sleep efficiency across ALL devices in the meta-analysis (not Fitbit specific). Statistically significant underestimation.

WHOOP strap (multiple generations across included studies)

All studies for this device →

Metric	Value	95% CI	Note
Bias (minutes)	see source	—	Lee et al. pooled WHOOP among 12 brands without per-device breakdown in the abstract. Consult the full paper for the per-device breakdown.

Garmin (multiple generations across included studies)

All studies for this device →

Metric	Value	95% CI	Note
Bias (minutes)	see source	—	Lee et al. pooled Garmin among 12 brands without per-device breakdown in the abstract. Consult the full paper for the per-device breakdown.

Xiaomi Mi Band 5

All studies for this device →

Metric	Value	95% CI	Note
Bias (minutes)	see source	—	Lee et al. included the Mi Band 5 (an earlier generation than the Smart Band 9 CircaTest covers) but did not break out per-device figures in the abstract.

Cite this study

Lee YJ, Lee JY, Cho JH, and Choi JH (2025). Performance of consumer wrist-worn sleep tracking devices compared to polysomnography: a meta-analysis. Journal of Clinical Sleep Medicine. https://doi.org/10.5664/jcsm.11460

AI-assembled record · errors are possible

This page was built and is maintained by AI working from the published abstract and PubMed metadata for the cited study. CircaTest does not have access to the full text of every paper in its corpus. Categories of error that have happened on this site and could happen again include:

Per-device metric values inferred when the abstract reports only an aggregate range
Stage-specific accuracy figures pulled from secondary sources rather than the primary paper
Sample size or population characteristics missing from the abstract
Editorial framing in the curatorial note that overstates the study's actual scope
Year typos and author-name transliteration errors

Where a metric value reads see source, the published abstract did not contain that value and CircaTest deliberately left it null rather than guess. For any decision that depends on the underlying numbers, please consult the linked PubMed, PMC, or DOI source directly. Corrections are welcome via the about page.

Source links

Added to the CircaTest meta-analysis on 2026-04-06. How CircaTest evaluates studies →