Monitoring sleep with 40-Hz ASSR

The 40-Hz auditory steady state response (ASSR) signals recorded from human subjects during sleep and wakefulness are investigated in this study for the purpose of monitoring sleep. The ASSR signals extracted from stimulated electro encephalogram (EEG), explored in search for differentiating and robust to noise features. Choosing appropriate features in time and frequency domain, the performance of linear and quadratic discriminant analysis in classifying signals in different scenarios are studied. While the developed method itself is novel in sleep monitoring, due to similarities between N3 stage of sleep and anesthesia, the method will pave the way for later analysis on monitoring consciousness with 40-Hz ASSR. The 40-Hz ASSR extraction and noise cancellation methods presented in this paper can also be used for extracting 40-Hz ASSR from its background EEG signal in general.