Changes in biological rhythms under conditions of mismatch between administrative time and natural time

Kalekeshov A. Junussova A. Makashev Y. Kyrbassova E. Parmanbekova M. Rizbekova A. Aitzhanova M. Massalimova R.
2026 University of Guilan

Caspian Journal of Environmental Sciences
2026 #24 Issue 1 25 - 38 pp.

It is well established that adequate and proper sleep is essential for the health of children and adolescents. This study examined the effect of a 1.5–2-hour difference between administrative and natural time in Kazakhstan on adolescents (n=120). In particular, adolescents in Atyrau, where administrative time is ahead of natural time, experienced chronic desynchronization. Consequently, this situation led to lowered sleep duration and quality, impaired cognitive performance, increased emotional instability, and compromised immune function. The predominance of “owl” and “dove” chronotypes among adolescents indicates a misalignment between their natural biological rhythms and school schedules. As a result, scores for memory, attention, and visual-motor reaction were below average. This decline in cognitive performance, particularly in the morning, negatively affected academic achievement. Notably, in the 9^th grade, when classes started earlier, grades dropped across all subjects, demonstrating the direct impact of desynchrony on learning efficiency. Physiological compensatory responses were observed in the respiratory system, including increased vital capacity of lungs and related indicators, and the cardiovascular system was also investigated. Additionally, a marked rise in disease incidence was noted among girls. These findings suggest that prolonged desynchronization has a significant impact on adolescent health.

Administrative time , Adolescent health , Biological rhythm , Desynchronosis , Natural time , Time zone

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Kazakh National Womens Teacher Training University, Almaty, Kazakhstan
Institute of Genetics and Physiology, Almaty, Kazakhstan
Isatai Taimanov secondary school, Atyrau, Kazakhstan

Kazakh National Womens Teacher Training University
Institute of Genetics and Physiology
Isatai Taimanov secondary school

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