Human chronotypes in the North

Long-term exposure to the climatic and social factors of the North cause desynchronization of the human circadian system, which can lead to an increase in the risk of age-associated diseases. Earlier, on a small sample, I showed that the higher the latitude at which a person resides in the North, the higher the frequency of the late chronotype. In addition, the parameters of diurnal rhythm in a late-chronotype subject are less expressed than in an early-chronotype one. The purpose of this study was to estimate the frequency distribution of various chronotypes depending on the latitude at which a person resides. Chronotypes were assessed by the Munich Chronotype Questionnaire (MCTQ). My study included 772 inhabitants of the Republic of Komi. It was shown that there was a significant northward trend towards a higher prevalence of the late chronotype. Thus, an increase in the frequency of the late chronotype, whose circadian rhythm is most sensitive to the negative action of climatic and social factors of the North, may be one of the causes of its desynchronization and an increase in the risk of age-associated diseases in northerners.