Heat acclimation alters the sleep and behavior based thermoregulatory dynamics of rats in heat stress - Original article - Medical Science - Volume 1 Issue 3 - Page no: 50-61

Background: It is well understood that the high environmental heat significantly affects the brain physiology of mammals, particularly the sleep and behavior of the subjects. The objective of the present work is to quantify the effects of acclimatization to the high environmental heat on sleep and behavioral activities in heat stress conditions. Methods: The polygraphic data involved simultaneous recordings of cortical electroencephalogram (EEG), electrooculogram (EOG), and electromyogram (EMG) were recorded both on chart as well as in digital format to study the sleep-wake parameters in three different age groups of freely moving rats following exposure to high environmental heat. Each age group was subdivided into four groups: the acute heat stress group, subjected to a single exposure of 4h at 38°C in the biological oxygen demand (BOD) incubator; the chronic heat stress group, exposed for 21 days, for 1 h each day, at 38°C in the BOD; acute heat stress followed by 21 days of chronic heat acclimatization and the handling control group. Open field and elevated plus-maze behavior was also analyzed following different exposure setup of high environmental heat. Results: The analyses of results suggest that acclimatization to the high environmental heat significantly alters the effects of acute exposure of high environmental heat on different sleep-wake as well as behavioral parameters. Conclusion: Acclimatization to environmental heat shifts the thermoregulatory set-point and thus these altered changes in sleep and behavior have been observed.