Midsagittal Jaw Movements as Sleep/Wake Marker
Abstract : The seriousness of the obstructive sleep apnea and hypopnea syndrome is measured by the apnea-hypopnea index (AHI), the number of sleep apneas and hypopneas over the total sleep time (TST). Cardio-respiratory signals are used to detect respiratory events while the TST is usually assessed by the analysis of electroencephalogram traces in polysomnography (PSG) or wrist actigraphy trace in portable monitoring. This paper presents a sleep/wake automatic detector that relies on a wavelet-based complexity measure of the midsagittal jaw movement signal and multi-layer perceptrons. 63 recordings were used to train and test the method while 38 recordings constituted an independent evaluation set for which the sensitivity, the specificity and the global agreement of sleep recognition reached respectively 85.1%, 76.4% and 82.9% compared with the PSG data. The AHI computed automatically and only from the jaw movement analysis was significantly improved (p < 0.0001) when considering this sleep/wake detector. Moreover, a sensitivity of 88.6% and specificity of 83.6% were found for the diagnosis of the sleep apnea syndrome according to a threshold of 15. Thus, the jaw movement signal is reasonably accurate in separating sleep from wake and, in addition to its ability to score respiratory events, is a valuable signal for portable monitoring.