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 nights where 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 = 1.94 minutes, SD = 1.32) and THIM sleep onset latency (mean = 2.05 minutes, SD = 1.38) on the first or second night (P > .07). There were moderate correlations between PSG and THIM on both nights [r > .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 THIM sleep onset latency (mean = 3.65 minutes, SD = 2.18) (P = .25). There was strong correspondence between the two devices [r > .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.