Fig. 3.

Diurnal rhythm of electroencephalogram delta power within non-rapid eye movement sleep (NREMS) epochs. Delta power fast Fourier transformation values for each 2-h block were divided by the sum of the 12 2-h blocks across the 24-h day to give a fractional percent of power within each 2-h block. Values shown are means ± SE. There were no significant strain differences; collectively, power was lower during daylight hours [zeitgeber time (ZT)0–ZT12] than during night hours as previously described for C57BL/6 mice (24, 47). *P < 0.05, light versus dark phase delta power.