A new method to analyze basic rest-activity cycle

A new method was proposed to analyze a basic rest-activity cycle (BRAC), te rmed BRAC-A. This method calculates a significant cycle length by chi-squar ed method and the starting points of a resting phase and an active one by a nalysis of the array consisting of the segmented time series in the same le ngth. Using 20 3-day computer-simulated time series of standard deviation i n fetal heart rate fluctuation with known periodicity of the BRAC, we demon strated that the BRAC-A was a useful tool to reveal the characteristics of the BRAC.