[Ala11,D-Leu15]-Orexin B(human) is a potent and selective orexin-2 receptor (OX2) agonist. [Ala11,D-Leu15]-Orexin B(human) shows a 400-fold selectivity for the OX2 (EC50=0.13 nM) over OX1 (52 nM).