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. 2019 Mar-Apr;17(2):124-136.
doi: 10.1080/15402002.2017.1300587. Epub 2017 Mar 21.

The Sleep of the Ring: Comparison of the ŌURA Sleep Tracker Against Polysomnography

Massimiliano de Zambotti  1 , Leonardo Rosas  1 , Ian M Colrain  1   2 , Fiona C Baker  1   3
Affiliations

The Sleep of the Ring: Comparison of the ŌURA Sleep Tracker Against Polysomnography

Massimiliano de Zambotti et al. Behav Sleep Med. 2019 Mar-Apr.

Abstract

Objective/Background: To evaluate the performance of a multisensor sleep-tracker (ŌURA ring) against polysomnography (PSG) in measuring sleep and sleep stages. Participants: Forty-one healthy adolescents and young adults (13 females; Age: 17.2 ± 2.4 years). Methods: Sleep data were recorded using the ŌURA ring and standard PSG on a single laboratory overnight. Metrics were compared using Bland-Altman plots and epoch-by-epoch (EBE) analysis. Results: Summary variables for sleep onset latency (SOL), total sleep time (TST), and wake after sleep onset (WASO) were not different between ŌURA ring and PSG. PSG-ŌURA discrepancies for WASO were greater in participants with more PSG-defined WASO (p < .001). Compared with PSG, ŌURA ring underestimated PSG N3 (~20 min) and overestimated PSG REM (~17 min; p < .05). PSG-ŌURA differences for TST and WASO lay within the ≤ 30 min a-priori-set clinically satisfactory ranges for 87.8% and 85.4% of the sample, respectively. From EBE analysis, ŌURA ring had a 96% sensitivity to detect sleep, and agreement of 65%, 51%, and 61%, in detecting "light sleep" (N1), "deep sleep" (N2 + N3), and REM sleep, respectively. Specificity in detecting wake was 48%. Similarly to PSG-N3 (p < .001), "deep sleep" detected with the ŌURA ring was negatively correlated with advancing age (p = .001). ŌURA ring correctly categorized 90.9%, 81.3%, and 92.9% into PSG-defined TST ranges of < 6 hr, 6-7 hr, > 7 hr, respectively. Conclusions: Multisensor sleep trackers, such as the ŌURA ring have the potential for detecting outcomes beyond binary sleep-wake using sources of information in addition to motion. While these first results could be viewed as promising, future development and validation are needed.

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Figures

Figure 1
Figure 1
Hypnogram (sleep stages plotted as a function of time of the night) from the ŌURA ring and polysomnography (PSG) obtained from a participant’s recording showing typical PSG-ŌURA discrepancies. REM, rapid-eye-movement.
Figure 2
Figure 2
Bland-Altman plots for total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), time in N1+N2 (“light sleep”) and time in N3 (“deep sleep”). Individuals’ PSG-ŌURA discrepancies on sleep metrics (y axis) are plotted as a function of the PSG metrics (x axis). Zero line and Biases are marked. The dotted lines represent the upper and lower Bland-Altman agreement limits (mean difference ± 1.96*SD). The dashed lines represent the upper and lower a priori-set clinically satisfactory limits for TST and WASO (± 30 min from the zero line).
Figure 3
Figure 3
Polysomnographic (PSG)-ŌURA discrepancies in “light sleep” and in rapid-eye-movement (REM) sleep as a function of ring position. Asterisks indicate significant (p < 0.05) differences from both “other” and “index” fingers.
Figure 4
Figure 4
Relationships between polysomnographic (PSG) N3 sleep (circles) and ŌURA “deep sleep”(triangles) with participants’ age.
See this image and copyright information in PMC

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