Study record · validation · 2018

A validation study of Fitbit Charge 2 compared with polysomnography in adults

de Zambotti M, Goldstone A, Claudatos S, Colrain IM, and Baker FC

Chronobiology International, 35(4), 465-476 · 2018

Why this study matters to CircaTest

First peer-reviewed PSG validation of a Fitbit model with sleep staging (the Charge 2 was the first staging-capable Fitbit). Establishes the per-stage accuracy figures (light 81%, deep 49%, REM 74%) that CircaTest's sleep-tracker-accuracy-explained guide uses to show that 'sleep score' aggregates can hide major per-stage variation.

Abstract

We evaluated the performance of a consumer multi-sensory wristband (Fitbit Charge 2) against polysomnography (PSG) in measuring sleep/wake state and sleep stage composition in healthy adults.…

Read the full abstract on the source →

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

Population

Sample size

n = 44

Age

19-61 years

Reference standard

psg

44 healthy adults (26 female), single in-laboratory overnight PSG with Fitbit Charge 2. Excluded subgroup with periodic limb movements analyzed separately.

Devices and metrics

Fitbit Charge 2

All studies for this device →

Metric	Value	95% CI	Note
Sensitivity	96%	—	Sensitivity to sleep.
Specificity	61%	—	Specificity for wake.
Light stage	81%	—	N1+N2 light sleep detection accuracy.
Deep stage	49%	—	N3 deep sleep detection accuracy.
REM stage	74%	—	REM sleep detection accuracy.
Bias (minutes)	9 min	—	TST overestimation vs PSG.

Cite this study

de Zambotti M, Goldstone A, Claudatos S, Colrain IM, and Baker FC (2018). A validation study of Fitbit Charge 2 compared with polysomnography in adults. Chronobiology International, 35(4), 465-476. https://doi.org/10.1080/07420528.2017.1413578

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 →