Influence of seasons on heart rate variability during cognitive activity in students with different types of daily activity

It is shown that changes of heart rate variability (HRV) in students with morning, afternoon and evening chronotypes under cognitive load are characterized by seasonal dependence. A more pronounced seasonal modulation of HRV is characteristic of "pigeons", whose background values of HRV parameters and responses to load during the school day are greater in the autumn-winter period than in the spring-summer period. In" larks", HRV changes in the conditions of cognitive activity dominate in the spring-summer season, and in "owls" – in the autumn-winter season, but the observed reactions are weaker than in "pigeons". The observed differences in HRV may be caused by seasonal features of mechanisms of the heart adaptation in different chronotypes. Keywords: heart rate variability, seasons of the year, chronotypes, cognitive load.