Effects of intracerebroventricular injection of UII into the PPT nucleus on the amount of W, SWS1, SWS2, and REM sleep across recording time. Values (mean ± SEM; n = 6 rats per group) represent the amount of the states of vigilance, expressed as a percentage of total time of recording. Significant effects of UII compared with the saline group were obtained using an unpaired bidirectional t test and are indicated by asterisks (for values, see Results). Error bars represent SEM.