An indicators analysis of the first-graders functional state and vegetative homeostasis obtained in the initial period of adaptation to the educational environment revealed gender differences in the rates of the adaptation process to new learning conditions. It has been established that girls’ adaptation mechanisms turn on earlier than boys’, with their similar orientation. The article provides an experimental justification of the indicators use legitimacy for heart rate variability to assess the functional state of the body in the acute period of adaptation to the educational environment. The importance of teacher physiological literacy for the optimization of the educational process is substantiated. The results of the study are convincing evidence of the knowledge importance for the physiological foundations of the occurrence and course of physiological and mental processes, stable individual psycho-physiological characteristics for the organization of the learning environment, corresponding to the functional capabilities of the body. This argument is also confirmed by many years of experience among master students key competencies development, which allow using such an objective criterion as the current functional state of the body to ensure, through the joint efforts of parents, teachers, psychologists, and doctors, the correction of the educational environment and psycho-physiological resistance of individual to it. The established differences in the dynamics of heart rate variability indicators for girls and boys can be used to form a health-saving program in school settings.