Annual dynamics of dispersion mapping indicators of electrocardiogram tracing in students with different chronotypes

The paper examines the annual profile of fluctuating microalternations of some ECG parameters in healthy students who live in northern conditions and have different chronotypes. The main method of the research was the dispersion mapping that helped assess the energy and metabolic processes in myocardium. Among male and female students, 14,3% had the morning chronotype, 50,7% had the arrhythmic chronotype, and 35% had the evening chronotype. Previously published research results showed a similar distribution of chronotypes among the population of the north: individuals with the arrhythmic chronotype dominate in the sample, the evening chronotype is the second most common, and the morning chronotype can be found in a smaller number of people. The seasonal dynamics of dispersion mapping indicators in students was analyzed. The analyses revealed an increase in the values of the Myocardium Index in students of all chronotypes in spring, with no significant deviations to be noted. The maximum values of the Heart Rate and Rhythm indicators in the annual dynamics in all students were noted in spring, and the minimum values, in summer, with significant deviations observed. The Rhythm integral indicator pointed to the signs of tension of adaptation mechanisms in the subjects with the evening chronotype in spring. Increased ECG microalterations (Myocardium, Heart Rate, Rhythm) in male and female students in spring may indicate the influence of climatic conditions that put a greater stress on the cardiovascular system in the transitional seasons. It is manifested by a change in the electrophysiological properties of the myocardium. In the subjects with the evening chronotype, the circadian rhythms of the circulatory system were more sensitive to the hypocomfortable conditions of the north.