<p>Periodic hypoxia is the episodic occurrence of hypoxia, which alternates with periods of reoxygenation and normoxia. Depending on the severity and duration of exposure, periodic hypoxia can lead to activation of both protective and pathological mechanisms. The aim of the study was to evaluate the dependence of the effects of periodic hypoxia on the age of rats. Male Wistar rats aged 2 and 4 months were used in the study. Half of the animals of each age were exposed to normobaric hypoxia (8% O₂, 2 hours) daily for 5 days. Subsequently, changes in body weight, anxiety levels, learning ability, and the activity of enzymes of the antioxidant system in the blood plasma were evaluated in rats. It has been shown that daily hypoxic exposure leads to a decrease in body weight and an increase in anxiety levels in male rats aged 2 and 4 months, as well as impaired learning ability in 4-month-old rats. In addition, age-dependent changes in the activity of enzymes of the glutathione antioxidant system in the blood were noted in rats exposed to hypoxia.</p>