Influence of undetected ECG R waves on the heart rate variability analysis

As the sleep disorders become the issue, we need to know the quality of ourselves sleep. In general, the quality of sleep is measured by polysomnography (PSG). But, this method is a time-consuming process. Therefore an easy method is needed. The estimation of sleep stages from a heart rate variability for 1 minute in sleep is a more easy method. A deepness of sleep and heart-rate variability is influenced by automatic nerve. They are closely related. Therefore, if we can know heart-rate in sleep, we can know the deepness of sleep. The algorism that estimate of sleep stage form heart-rate are known. But, when a subject turned over, the R waves of heart-rate is undetected. In general, the sleep stages in the 1 minutes are not estimated. It is possible to estimate sleep stages if there are several undetectable R waves. LF and HF obtained from ECG are used to estimate sleep stage. And so, in this paper, we verify whether to estimate LF and HF from heart rate, when heart-rate is undetected.