Double-plotted actogram demonstrating how drugs of abuse can impact the expression of daily rhythms. This rat self-administered cocaine on the indicated days/time (*) resulting in a clear shift to daytime activity during drug administration compared to the normal nocturnal activity. Shading indicates darkness. Days are indicated on the left and time of day across the top of the figure.
Juvenile Grizzly Bear
Double-plotted actogram demonstrating how the daily light:dark cycle organizes activity of a young grizzly (brown) bear in captivity. This bear is diurnal (day active). On day 70, the bear was transferred to an isolation facility and maintained in complete darkness while hibernating (day 70-165). Light was then applied (*) for 1 or 4h. Light exposure was associated with delays and advances of the subsequent activity depending on when it was applied. Days are indicated on the left and time of day across the top of the figure. Shading indicates darkness.