Head Movement Model during Sleep Onset under Sitting Conditions with 3 Levels of Sleep Depth as Input

Abstract

Under sitting conditions, up-and-down head movements occur during the transition period from awakening to stage 2 non-REM sleep. This paper proposes a model that calculates head movements by giving time series of three sleep depths. The proposed model couples a head musculoskeletal model with a muscle activity model. The former is represented by an antagonistic drive system based on muscle contraction characteristics, while the latter varies the magnitude of muscle activity level according to sleep depth. We first measured variations in EEG/EMG around the neck and cervical angle during sleep onset, and based on these characteristics, we constructed two models and developed the proposed model. We then conducted numerical simulations to examine whether the proposed model can represent actual head movements and compared the simulation results with experimental results. The simulation results concluded that the proposed model can represent the experimental results and that the muscle activity waveforms generated in the intermediate stage have experimental characteristics. This model suggests that drowsiness can be estimated from head movements and is expected to be applied to estimate driver's drowsiness.