The accuracy of the THIM wearable device for estimating sleep onset latency

Study Objectives: THIM is a wearable device designed to accurately estimate sleep onset. This article presents 2 studies that tested the original (study 1) and a refined (study 2) THIM algorithm against polysomnography (PSG) for estimating sleep onset latency. Methods: Twelve (study 1) and 20 (study 2) individuals slept in the laboratory on 2 nightswhere participants underwent THIM-administered sleep onset trials with simultaneous PSG recording. Participants attempted to fall asleep while using THIM, which woke them once it determined sleep onset. Results: In study 1, there was no significant difference between PSG(mean = 1.94minutes, SD = 1.32) and THIM sleep onset latency (mean = 2.05minutes, SD = 1.38) on the first or second night (P >.07). There were moderate correlations between PSG and THIM on both nights [r(s) > .57, P <.001]. In 23.74% of trials, PSG sleep onset could not be determined before THIM ended the trial.With a revised THIM algorithm in study 2, there was no significant difference between PSG (mean = 3.41 minutes, SD = 2.21) and THIMsleep onset latency (mean = 3.65 minutes, SD = 2.18) (P =.25). There was strong correspondence between the two devices [r(s) > .73, P <.001], narrow levels of agreement on Bland-Altman plots, and significantly fewer trials where PSG sleep onset had not occurred (10.24%), P = .04. Conclusions: THIM showed a high degree of correspondence and agreement with PSG for estimating sleep onset latency. Future research will investigate whether THIM is accurate with an insomnia sample for clinical purposes.