Fig. 9. Changes in sleep vigilance related to the hypnotic effects of olanzapine in a neuropathic pain-like state as determined by electroencephalogram and electromyogram recordings. Sleep–wake states after the injection of vehicle (5% dimethyl sulfoxide) or olanzapine at 7 days after sciatic nerve ligation. Vehicle or olanzapine (0.06 mg/kg, intraperitoneal administration) was injected once at 8:00 AM. The total time spent in wakefulness in the light phase (A ) and the dark phase (D ), rapid eye movement (REM) sleep in the light phase (B ) and in the dark phase (E ), and non-REM sleep in the light phase (C ) and in the dark phase (F ) was determined by electroencephalogram and electromyogram recording. Each column represents the mean ± SEM of five mice. Statistical analyses were performed with Student t test. **P = 0.0067, ***P = 0.0009 versus sham-vehicle; ##P = 0.001, ###P = 0.0006 versus nerve ligation-vehicle.