Statistical and dynamical analysis of circadian rhythms.

Time series of core temperature in golden hamsters with or without access to a running wheel were analyzed using statistical tools and Dynamical Systems theory. Although the statistical analysis did not show any striking difference between the two groups (other than clearer spectra in the case in the animals with access to wheels), a clear dynamical difference was found. The circadian temperature of hamsters with access to wheel running exhibited fewer degrees of freedom than those without access to them (1.728 vs 11.548). Thus, it may be argued that wheel running synchronizes the ciradian organization of hamsters.