Research Of Sleep Stage Based On ECG Signal During Day Time Nap Sleep

The research of sleep is an important topic, the sleep can be separated into two classes, which are long time sleep in the night and short nap sleep in daytime, their mechanism and functions are very different. During the sleep, people would make different intensity of reaction for the external stimulate, which is called vigilance level, it is meaningful for analyzing the sleep stage.This paper was mainly research the vigilance level of people's day time nap sleep, then recognized the sleep stage based on it. There were lots of people who had done lots of works about sleep stage based on EEG signal, based on this, the paper proposed to analyze vigilance level and sleep stage based on ECG signal during day time nap sleep. The previous studies were focus on EEG and night sleep to analyze vigilance level, but here, the study was focus on ECG signal and day time nap sleep to analyze vigilance level. The different stages of different signals were compared, and then the features were combined, the result indicated that when the ECG signal were combined with EEG signal, the accuracy rate of sleep stage was improved.Firstly, the recorded ECG signal was preprocessed and the heart rate variability was calculated. Although there were lots of methods to detect R wave, this paper proposed a new method to detect the peak of R wave, this method was simple and the accuracy rate of detection was high. The HRV was analyzed, the 10 features were extracted,6 features in time domain and 4 features in frequency domain. Next, all the features were analyzed, the redundant parameters were removed, the useful features were left to analyze. Based on these features, the day time nap sleep was classified with SVM, and then compared the result with the result from EEG signal, the result showed that this can improve the accuracy rate of sleep stage from 74.42% to79.07%.