Nature and Science of Sleep (Jan 2021)
The Development and Accuracy of the THIM Wearable Device for Estimating Sleep and Wakefulness
Abstract
Hannah Scott,1,2 Nicole Lovato,2 Leon Lack1,2 1College of Education, Psychology and Social Work, Flinders University, Adelaide, SA, 5001, Australia; 2Adelaide Institute for Sleep Health: AFlinders Centre of Research Excellence, College of Medicine and Public Health, Flinders University, Adelaide, SA, 5001, AustraliaCorrespondence: Hannah ScottCollege of Education, Psychology and Social Work, Flinders University, GPO Box 2100, Adelaide, SA, 5001, AustraliaTel + 61 8 8201 2767Email [email protected]: THIM is a new wearable device worn on the finger that can passively monitor sleep and wakefulness overnight using actigraphy. This article showcases the development of the THIM sleep tracking algorithm (Study 1) and the testing of its accuracy against polysomnography (PSG) with an independent sample of good and poor sleepers (Study 2). The accuracy of THIM was compared to two popular wearables, Fitbit and Actiwatch devices.Methods: Twenty-five (Study 1) and twenty (Study 2) healthy individuals with good or poor sleep (defined by scores on the Insomnia Severity Index) slept overnight in the sleep laboratory on one night. Participants slept from their typical bedtime to their typical wake up time with simultaneous recording from PSG, THIM, Fitbit and Actiwatch devices.Results: In both studies, THIM had lower sensitivity (M = 0.89– 0.91) compared to the Actiwatch (M = 0.95) and Fitbit devices (M = 0.96– 0.98), yet higher specificity (M = 0.59 vs M = 0.32– 0.59) in detecting sleep. There were no significant differences between PSG and THIM in either study for sleep onset latency, total sleep time, wake after sleep onset, or sleep efficiency, p > 0.06. Yet, there was high variability in the accuracy of all three actigraphy devices between individuals (evident on Bland–Altman plots) that was unexplained by sleep quality.Discussion: Together, these studies suggest that THIM is capable of monitoring sleep and wake overnight in good and poor sleepers to a similar degree of accuracy as two of the most popular actigraphy devices available. Future research will examine the accuracy of THIM for monitoring sleep in people with insomnia.Keywords: wearable technology, consumer sleep technology, polysomnography, actigraphy, sleep parameters, validation
