FIELD: medicine. SUBSTANCE: method involves monitoring electrocardiogram the whole day long, selecting the value of mean heart beat rate (strokes per 1 min) separately in sleeping and awakening periods. Circadian index is determined as ratio of mean diurnal heart beat rate value per 1 min to mean nocturnal one. The index value being from 1.24 to 1.44, stable organization of circadian rhythm is found to take place both in healthy and ill people possessing no marked injuries of intracardiac and vegetative centers of cardiac activity circadian rhythm regulation. The circadian index value describing cardiovascular and vegetative nerve system state does not depend on sex, age of patients, basic rhythm nature and devices used. EFFECT: enhanced accuracy of the method. 1 tbl
