Ultradian Near 2-4-h Rhythms of Body Temperature in Laboratory Rodents Depend on External Environmental Heliogeophysical Factor Reflected by Neutron Monitor Count Rate.

The study collated oscillations of body temperature of С57BL/6 mice and Roborovski hamsters (Phodopus roborovskii) in the period range of 100-240 min and fluctuations of the secondary cosmic rays reflected by neutron count rate of a neutron monitor at the Earth's surface. Cross-correlation of body temperature and neutron count rate data revealed their strong association only for simultaneous measurements. Collation of the phase of neutron count rate fluctuations with maxima of body temperature oscillations revealed the coincidence of the phases of both processes. There was a temporary connection between the periods of body temperature elevation and neutron count rate rise. Thus, not only the spectral parameters of biological and physical processes, but also their phases coincided, which corroborates the hypothesis on stimulating effect of increasing neutron count rate on activity of the animals.