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Volume 14 No. 10
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Accepted Papers

Emerging Technologies

An Evaluation of the NightOwl Home Sleep Apnea Testing System

Frederik Massie, MSc1; Duarte Mendes de Almeida, MSc1; Pauline Dreesen, MSc2; Inge Thijs, MSc, PhD2; Julie Vranken, MSc2; Susie Klerkx, MD3
1Ectosense NV, Leuven, Belgium; 2Future Health Department, Ziekenhuis Oost-Limburg (Hospital East-Limburg), Genk, Belgium and Mobile Health Unit, Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium; 3Department of Pneumology, Ziekenhuis Oost-Limburg (Hospital East-Limburg), Genk, Belgium

Study Objectives:

The objective of this study was to evaluate the performance of a miniaturized home sleep apnea test, called NightOwl. The system consists of a sensor placed on the fingertip and a cloud-based analytics software. The sensor acquires accelerometer and photoplethysmographic data. The software derives actigraphy from the former, and blood oxygen saturation and peripheral arterial tone, among other features, from the latter.


Data of 101 participants who underwent an in-laboratory polysomnography (PSG), while wearing the NightOwl sensor, were collected. In order to establish an external benchmark, all PSG tests were edited by a somnologist of Younes Medical Technologies Ltd. (YMT) after analysis by the Michele Sleep Scoring System (MSSS). The respiratory event index (REI) derived by NightOwl (NightOwl-REI), the apnea-hypopnea index (AHI) derived by Ziekenhuis Oost-Limburg (ZOL-AHI), and the AHI derived by YMT (MSSS-AHI) were compared.


The NightOwl-REI had a high correlation with the MSSS-AHI (ρ = .87, P < .001), which was close to the correlation between the ZOL-AHI and MSSS-AHI (ρ = .84, P < .001). The NightOwl-REI and ZOL-AHI had a correlation of .77 (P < .001). After categorization of the AHI, the agreement between the NightOwl-REI and the MSSS-AHI was .812 and the agreement between the ZOL-AHI and MSSS-AHI was .743, after double-labeling near-boundary participants.


The NightOwl-REI achieved a close correlation and REI-categorization with the MSSS-AHI, especially in light of the significant inter-scorer variability of the analysis of the PSG.


Massie F, Mendes de Almeida D, Dreesen P, Thijs I, Vranken J, Klerkx S. An evaluation of the NightOwl home sleep apnea testing system. J Clin Sleep Med. 2018;14(10):1791–1796.

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