Insufficient sleep could severely impair both cognitive and learning skills. More prominent changes are found in children and adolescents. Tools used to estimate sleepiness in the adult population are commonly inappropriate for children. The objective of our study was to provide a reliable instrument to measure excessive sleepiness for upcoming studies in Russian-speaking children, applying the Russian version of Pediatric Daytime Sleepiness Scale (PDSS). The following tasks were resolved in our study: translation, validation, and analysis of psychometric properties of the Russian adaptation of the PDSS by standard tests. After the semantic validation of the instrument through a multi-stage translation process we checked its psychometric validation. A total of 552 students, consisting of N = 285 for the exploratory factor analysis (EFA), N = 267 for the confirmatory factor analysis (CFA) and N = 204 for test-retest analysis of public elementary schools located in Northern Russia completed the PDSS and Munich Chronotype Questionnaire to estimate sleep parameters in the classroom during the lessons. Response rate was 90%; excluded cases contained no data. Further, 204 of our participants completed the PDSS in a 3 months interval to check the test-retest reliability. Internal consistency was measured by Cronbach's alpha coefficients and CFA was used to test factorial validity of the tool. Concurrent validity and test-retest reliability were assessed via intra-class coefficient. Internal consistency of the PDSS scale was high (Cronbach's α = 0.8). The construct validity of the PDSS was supported by CFA (factor loadings were from 0.438 to 0.727) and the test-retest reliability demonstrated by the intra-class coefficient was 0.70. The total PDSS score was independent of sex. The mean total value of PDSS was 11.95 ± 6.24. Higher scores on PDSS were negatively correlated with sleep duration. Thus, the construct validity of the instrument remains valid and could be used for Russian-speaking youth samples in the evaluation of daytime sleepiness. It could be useful in future applications by sleep scientists and health practitioners.

The influence of variations in solar, geophysical, and meteorological factors, as well as of the lunar cycle phases, on cardiohemodynamic, emotional and CNS parameters has been studied in 12 men (19-38 years old) permanently residing in the Arctic region (the town of Apatity, 67°57′ N, 33°39′ E). The period of observation was characterized by M1 and M2 class solar flares and G1-G3 class geomagnetic storms. The study has demonstrated the adaptive modulation effects of environmental factors on autonomic regulation systems and the perturbing influences of geomagnetic storm and solar chromospheric flares on human func tional state. Multiple regression analysis was used to identify the dominant environment factors by the degree of their influence on functional parameters and to assess their combined effect. The coefficient of determi nation was no more than 0.5 on average; however, in some subjects, it reached 0.7-0.8 for certain parameters. All subjects were shown to respond to the permanent fluctuations of climatic-geographical and cosmophys ical factors under the extreme conditions of high latitudes; however, response pattern and intensity depended on individual sensitivity to their isolated and combined effects.

The age dynamic of parasympathetic and sympathetic activity of autonomous nervous system (ANS) in the heart rate (HR) regulation is considered in the article from the perspective of allostasis theory. Two groups of people are compared: working residents of Arctic region (aged from 20 till 75 years old, divided in 10-years age cohorts, total 267 people) and working residents of the Central Part of Russia (116 people). The model of allostatic influence on the organism's regulatory systems in the process of adaptation to the conditions of high latitudes is studied compared to clustered data of HR analysis recorded in the background. The model of allostasis implies to support an organism's inner stability not from the perspective of body balance control but through changes preservation according to external conditions. «The adaptation cost» as a result of allostaric load is described by means of peculiarities of HR regulation in indifferent groups of surveyed. A method of human adaptation potential assessment by means of the analysis of ANS parasympathetic parts contribution to HR regulation is rested and discussed in the article. This approach allows to reveal risk group candidates for adaptation process breakdown.

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