Effects of the injection of hypocretin-1 into the nucleus pontis oralis on the latency (A), percentage (B), frequency (C) and duration (D) of wakefulness, quiet sleep, and active sleep during the first hour following its injection during quiet sleep. The bars represent mean values; error bars indicate the SEM of each population. A: Graphs highlight the latency to the onset of the first episode of active sleep and wakefulness following injections of hypocretin-1 (n = 14) and saline (n = 10). Note that hypocretin-1 significantly reduced the mean latency to active sleep. B: Histograms illustrating the percentages of behavioral states following the injection of hypocretin-1, which significantly increased the time spent in active sleep and decreased the amount of wakefulness, compared with injections of saline. C: Graphs present the number of episodes of behavioral states per hour (frequency) following the injection of hypocretin-1 and saline. Injections of hypocretin-1 significantly increased the frequency of episodes of active sleep. D: Graphs showing that injections of hypocretin-1 significantly reduced the mean duration of episodes of wakefulness. Asterisks indicate the levels of statistical significance of the difference between means: **P < 0.01, ***P < 0.001 by unpaired t-test.