Fig. 5.

Double-plotted wheel-running records of two wild-type C57BL/6J mice that entrained diurnally to the dim-light:dark cycle. Yellow bars at the top of each record indicate the time of lights-on. For the first 2 weeks of each record, animals were housed in a standard-intensity (150 μW/cm²) LD12:12 cycle. On the days indicated by the upper arrows, the light intensity during the light phase was dimmed to 0.0001 μW/cm² by covering the fluorescent bulbs with a neutral density filter. On the day indicated by the lower arrow, mice were released into DD.