An OX2R antagonist; selective for OX2R over OX1R (IC50s = 18 and 1,789 nM, respectively); decreases the amount of time spent in active wake and increases the time spent in REM sleep and SMS in mice, rats, dogs, and rhesus monkeys at 100, 20, 1, and 10 mg/kg, respectively; inhibits restraint stress-induced increases in plasma ACTH levels and struggle behavior, as well as decreases in body weight, at 30 mg/kg in rats expressing the hM3Dq DREADD activated by CNO in orexin neurons