Electroencephalogram (EEG) and electromyogram (EMG) after morphine administration. Morphine was administered subcutaneously at a dose of 5 mg/kg. (A) Raw EEG and electromyogram traces in a rat at 10 min before the administration of morphine (baseline). (B) Raw EEG and electromyogram traces of the same rat at 50 min after the subcutaneous administration of morphine before administration of orexin-A (postmorphine/pre–orexin-A). Short epochs of increased power were observed. (C) Spectral power of electromyogram did not differ between baseline and postmorphine/pre–orexin-A (n = 6 for each group; frequency × group effect: P = 1.000, two-way repeated measures ANOVA; error bars = SD). (D) Mean power frequency of electromyography did not differ between baseline and postmorphine/pre–orexin-A (n = 6 for each group; P = 0.450, paired t test; error bars = SD).