ローレンツプロットの定量評価による睡眠推移の推定

抄録

In the present study, it is intended to helpfully estimate the depth of sleep during all night with RR intervals (RBIs) in order to monitor a daily life sleep in real-time. Analysis of electrocardiogram's RBIs was used a Lorenz plot (LP). To evaluate quantitatively the changes in these distributions, RRIs are projected a LP on a y = x axis, y = -x axis, and considered as an ellipse which was composed of a long axis σ(x), a short axis σ(-x). We calculated the shifting of the mean (center C) and standard deviation (area S) for each sleep levels. Its analysis periods for 60sec were between n-60th and nth and shifted for every 1 second of data. As a result, center C showed the process toward light sleep level, area S showed the transition phase toward deep sleep level. Sum differences of Center C and area S were set each the thresholds and estimated transition phases of sleep level using the algorithm. A mean of concordance rate was 60.9% between estimated values and measured values which were actual transition of sleep levels. Therefore, the transitional sleep level can be evaluated based on heart rate variability by using LP.