Performance of seven consumer sleep-tracking devices compared with polysomnography

Abstract

Study objectives: Consumer sleep-tracking devices are widely used and becoming more technologically advanced, creating strong interest from researchers and clinicians for their possible use as alternatives to standard actigraphy. We, therefore, tested the performance of many of the latest consumer sleep-tracking devices, alongside actigraphy, versus the gold-standard sleep assessment technique, polysomnography (PSG).

Methods: In total, 34 healthy young adults (22 women; 28.1 ± 3.9 years, mean ± SD) were tested on three consecutive nights (including a disrupted sleep condition) in a sleep laboratory with PSG, along with actigraphy (Philips Respironics Actiwatch 2) and a subset of consumer sleep-tracking devices. Altogether, four wearable (Fatigue Science Readiband, Fitbit Alta HR, Garmin Fenix 5S, Garmin Vivosmart 3) and three nonwearable (EarlySense Live, ResMed S+, SleepScore Max) devices were tested. Sleep/wake summary and epoch-by-epoch agreement measures were compared with PSG.

Results: Most devices (Fatigue Science Readiband, Fitbit Alta HR, EarlySense Live, ResMed S+, SleepScore Max) performed as well as or better than actigraphy on sleep/wake performance measures, while the Garmin devices performed worse. Overall, epoch-by-epoch sensitivity was high (all ≥0.93), specificity was low-to-medium (0.18-0.54), sleep stage comparisons were mixed, and devices tended to perform worse on nights with poorer/disrupted sleep.

Conclusions: Consumer sleep-tracking devices exhibited high performance in detecting sleep, and most performed equivalent to (or better than) actigraphy in detecting wake. Device sleep stage assessments were inconsistent. Findings indicate that many newer sleep-tracking devices demonstrate promising performance for tracking sleep and wake. Devices should be tested in different populations and settings to further examine their wider validity and utility.

Keywords: actigraphy; nearables; noncontact; polysomnography; sensors; sleep technology; validation; wearables.

© Sleep Research Society 2020. Published by Oxford University Press on behalf of the Sleep Research Society.

Figures

Figure 1.

Bland–Altman plots: total sleep time (TST). Bland–Altman plots depicting the mean bias (blue dashed line) and upper and lower limits of agreement (two standard deviations from bias; black dashed lines) for minutes of TST for the devices compared with polysomnography (PSG). Black circles are individual nights. Solid blue curves represent the best-fit of data, with surrounding gray shaded regions representing 95% confidence bands. The solid black line at zero represents no difference, with positive and negative y-axis values indicating an overestimation or underestimation, respectively, compared with PSG.

Figure 2.

Bland–Altman plots: sleep efficiency (SE). Bland–Altman plots depicting the percentage of SE for the devices compared with polysomnography (PSG). See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.

Figure 3.

Bland–Altman plots: sleep onset latency (SOL). Bland–Altman plots depicting the minutes of SOL for the devices compared with polysomnography (PSG). See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.

Figure 4.

Bland–Altman plots: wake after sleep onset (WASO). Bland–Altman plots depicting the minutes of WASO from sleep onset latency (SOL) for the devices compared with polysomnography (PSG). See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.

Figure 5.

Bland–Altman plots: light sleep. Bland–Altman plots depicting the minutes of light sleep for the devices compared with polysomnography (PSG). For PSG, light sleep was calculated as the combination of N1 and N2 sleep stages. Only devices that output data on sleep stages are depicted. See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.

Figure 6.

Bland–Altman plots: deep sleep. Bland–Altman plots depicting the minutes of deep sleep for the devices compared with polysomnography (PSG). For PSG, deep sleep was calculated as the N3 sleep stage. Only devices that output data on sleep stages are depicted. See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.

Figure 7.

Bland–Altman plots: rapid eye movement (REM) sleep. Bland–Altman plots depicting the minutes of REM sleep for the devices compared with polysomnography (PSG). Only devices that output data on sleep stages are depicted. See Figure 1 caption for additional details on the interpretation of Bland–Altman plots.