Abstract: The present invention collects data on circadian intervals between two cardiac contractions (RR intervals) and, on the basis of the collected data on circadian RR intervals, provides a system for analysis of the human circadian heart rhythm autonomic nervous system balance, and analysis of heart rate (HR). The invention focuses on HR fluctuations that are divided into three groups: slow fluctuations of the circadian period, higher frequencies compared with circadian, and chaotic. The division into parts is executed by applying adequate empiric and mathematical methods to determine a series of envelope curves, closely and individually related to the principal circadian series, followed by their separation from the input HR series, and then applying HR variability (HRV) methods to increase accuracy of the analysis of HRV results and add new HR regulation criteria to the analysis outcomes.