M.A. Ovsyankina - Lecturer, Arkhangelsk Pedagogical College (Arkhangelsk) E-mail: marinaovsyankina@mail.ru L.V. Poskotinova - Dr.Sc. (Biol.), Associated Professor, Head of Biorhythmology, Federal Center for Integrated Arctic Researches, Russian Academy of Sciences (Arkhangelsk) E-mail: liliya200572@mail.ru E.V. Krivonogova - Ph.D. (Biol.), Senior Research Scientist, Federal Center for Integrated Arctic Researches, Russian Academy of Sciences (Arkhangelsk) E-mail: elena200280@mail.ru