Sleep Monitoring with Intraorally Measured Photoplethysmography (PPG) Signals

According to statistical reports, the number of people suffering from a sleep disorder is increasing as the population ages, and untreated sleep disorders lead to serious illness. Unfortunately, the development of sleep disorders cannot be monitored regularly at present, even after diagnosis. This study proposes an intraoral PPG-based sleep monitoring system to measure PPG signals from the oral cavity and predict different sleep stages in addition to estimating apnea-hypopnea index (AHI). The proposed sleep monitoring system can be integrated into an oral appliance to be worn during sleep, thanks to its physical aspect and water resistance. The accuracy of the estimation of heart rate (HR) and blood oxygen saturation (SpO2) parameters is validated in comparison with two FDA-approved pulse oximeters placed at the conventional anatomic site, the finger. It is experimentally shown that the proposed intraoral sleep monitoring system, in conjunction with the applied algorithm, can estimate total sleep time, rapid-eye movement (REM) time, and AHI with 92%, 75%, and 84% accuracy, respectively, compared with a home sleep apnea testing module for.