Daytime Sleep-Tracking Performance of Four Commercial Wearable Devices During Unrestricted Home Sleep

Abstract

Purpose

Previous studies have found that many commercial wearable devices can accurately track sleep-wake patterns in laboratory or home settings. However, nearly all previous studies tested devices under conditions with fixed time in bed (TIB) and during nighttime sleep episodes only. Despite its relevance to shift workers and others with irregular sleep schedules, it is largely unknown how devices track daytime sleep. Therefore, we tested the sleep-tracking performance of four commercial wearable devices during unrestricted home daytime sleep.

Participants and Methods

Participants were 16 healthy young adults (6 men, 10 women; 26.6 ± 4.6 years, mean ± SD) with habitual daytime sleep schedules. Participants slept at home for 1 week under unrestricted conditions (ie, self-selecting TIB) using a set of four commercial wearable devices and completed reference sleep logs. Wearables included the Fatigue Science ReadiBand, Fitbit Inspire HR, Oura Ring, and Polar Vantage V Titan. Daytime sleep episode TIB biases and frequencies of missed and false-positive daytime sleep episodes were examined.

Results

TIB bias was low in general for all devices on most daytime sleep episodes, but some exhibited large biases (eg, >1 h). Total missed daytime sleep episodes were as follows: Fatigue Science: 3.6%; Fitbit: 4.8%; Oura: 6.0%; Polar: 37.3%. Missed episodes occurred most often when TIB was short (eg, naps <4 h).

Conclusion

When daytime sleep episodes were recorded, the devices generally exhibited similar performance for tracking TIB (ie, most episodes had low bias). However, the devices failed to detect some daytime episodes, which occurred most often when TIB was short, but varied across devices (especially Polar, which missed over one-third of episodes). Findings suggest that accurate daytime sleep tracking is largely achievable with commercial wearable devices. However, performance differences for missed recordings suggest that some devices vary in reliability (especially for naps), but improvements could likely be made with changes to algorithm sensitivities.

Keywords:

• validation
• consumer sleep technology
• naps
• habitual sleep
• shift work
• sleep diary

Abbreviations

LOA, limits of agreement; PPG, photoplethysmography; PSG, polysomnography; SD, standard deviation; TIB, time in bed.

Data Sharing Statement

The datasets generated and/or analyzed during the current study are not publicly available due to security protocols and privacy regulations, but they may be made available on reasonable request by the Naval Health Research Center Institutional Review Board (contact phone [phone]).

Acknowledgments

This research was funded by the Office of Naval Research, Code 34. The authors wish to thank Prayag Gordy for support with data analysis and visualization, and Liliya Silayeva, PhD, for helpful comments on the manuscript and project management support. Rachel R. Markwald is an employee of the US Government. This work was prepared as part of her official duties. Title 17, USC. §105 provides that copyright protection under this title is not available for any work of the US Government. Title 17, USC. §101 defines a US Government work as work prepared by a military service member or employee of the US Government as part of that person’s official duties. Report No. 22–81 was supported by the Office of Naval Research, Code 34, under work unit no. N1701. The views expressed in this article reflect the results of research conducted by the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the US Government. The study protocol was approved by the Naval Health Research Center Institutional Review Board in compliance with all applicable federal regulations governing the protection of human subjects. Research data were derived from an approved Naval Health Research Center Institutional Review Board protocol, number NHRC.2017.0008.

Disclosure

The authors report no conflicts of interest in this work.