Fig. 2.

The MT₂ receptor partial agonist UCM765 promotes non–rapid eye movement sleep (NREMS; modified from Ochoa-Sanchez and colleagues,³³ with permission). (Top right) Schematic depiction of a rat with electrodes implanted for electroencephalography (EEG) and electromyography (EMG) recordings. (Top left) Example of an EEG/EMG recording highlighting a period of wakefulness, NREMS and rapid-eye movement sleep (REMS). (Bottom) The effect of UCM765 (40 mg/kg, subcutaneous) on NREMS latency, NREMS time, REMS time, wakefulness time and number of sleep spindles during the light and dark phases of the 12:12 hour light–dark cycle. **p < 0.01 and ***p < 0.001 versus vehicle, 2-way mixed-design analysis of variance plus Newman–Keuls test for post hoc comparison.