Association between Ultradian Rhythms of Body Temperature and Fluctuations in Atmospheric Pressure

The study examined the relationship between ultradian rhythms of body temperature (BT) in young (1-month-old) Djungarian hamsters (Phodopus sungorus) and fluctuations in atmospheric pressure (AP). A stable positive correlation was identified between BT variations and AP changes, most prominently during the animals' daily active phase. This association was especially pronounced during periods of rising AP. Harmonic analysis revealed synchronized rhythmic components in both BT and AP within the 12-30-min period range. However, experimentally induced (artificial) oscillations in AP did not elicit corresponding changes in BT, indicating that AP fluctuations alone do not drive the observed physiological rhythms. These findings suggest that the natural 12-30-min AP oscillations observed under stable weather conditions likely serve as external markers of an underlying biotropic factor that modulates the animal activity rhythms rather than acting as a direct causal stimulus.