Photoperiodic stability of chronotype

Aim. Development and evaluation of the photoperiodic stability index of the human chronotype in the conditions of the northern region. Results. A model for assessing the seasonal dynamics of the biorhythmic stereotype is proposed. In the summer season, the shift of the maximum total points towards a decrease, the minimum - towards an increase, is revealed. In this case, intermediate values do not fluctuate. Conclusion. The results of the study allow us to recommend the determination of the index of photoperiodic stability of the chronotype for the assessment of physiological fluctuations of individual chronotypological properties.