Accuracy validation of sleep measurements by a contactless biomotion sensor on subjects with suspected sleep apnea

Due to the busy lifestyles of people in developed countries, insufficient sleep has emerged as a central health issue in the general population. Objective home sleep monitoring is preferable for identifying sleep problems and improving sleep quality. Several instruments, most notably wrist actigraphy, have been used for this purpose. However, various impediments, including economic and practical concerns, have continued to hamper the widespread use of self-sleep monitoring. In this study, we used the contactless biomotion sensor based on SleepMinder™ with a frequency band modified from 5.8 GHz to 10.525 Hz to comply with Japanese Radio Law. The purpose of the study was to validate the accuracy of the sleep-wake algorithm for adult outpatients used by this new sensing system. We examined the data using simultaneous polysomnography and compared the results with previous contactless biomotion sensor and actigraphy studies. Data were collected at two institutions, the Ota Memorial Sleep Center and Kuwamizu Hospital. In total, 211 adult subjects participated in the study, and 148 (99 subjects with apnea-hypopnea index score 15) were used for the analysis. The overall accuracy of the new system was 84.1%, and its sensitivity and specificity were 91.8% and 37.6%, respectively. The automated algorithm slightly overestimated total sleep time (bias: +13 min) and sleep efficiency (bias: +3%) compared with polysomnography. As for sleep onset latency and wake time after sleep onset, these were slightly underestimated. The results are comparable to previous contactless biomotion sensor and actigraphy studies, and indicate that this modified contactless biomotion sensor is sufficiently accurate for monitoring sleep-wake patterns in this population.