Figure 4.

Mean proportion of time spent by postnatal day (P)9, P11, and P13 rats in wakefulness (W), quiet sleep (QS), and active sleep (AS) determined using Criterion 1 (A) or Criterion 2 (B). See Figure 3A for comparison between 2 criteria. Because delta activity is not found at P9, Criterion 2 cannot be applied to subjects at that age. *Significantly different from other 2 states within an age. Mean + SEM.