Figure 6.

Activity and cardiovascular cycles are highly consistent across days. Both the patterns and amplitudes of activity and cardiovascular measures were remarkably consistent from day to day. Smoothed data from a single animal are presented in three overlaid 24 hour segments to illustrate the day-to-day consistency of the voles’ ultradian rhythms. This animal appears to show a circadian pattern (lower values during the lights-off period) but as a group, the voles did not display significant light-dark differences. Slightly greater activity was seen at the lights-on and lights-off transitions also were seen in some, but not all, animals. Light and dark periods are indicated by the black and white bar. 6710 is the animal number