A melatonin receptor agonist (Kis = 14, 112, and 23.1 pM for human MT1, human MT2, and chick forebrain receptors, respectively); selective for MT1 and MT2 over MT3 receptors (Ki = 2.65 μM for hamster brain MT3 receptors) as well as a panel of benzodiazepine, dopamine, and opiate receptors, ion channels, transporters, and enzymes when used at a concentration of 10 μM; stimulates cAMP production in CHO cells expressing human MT1 and MT2 receptors (IC50s = 21.2 and 53.4 pM, respectively); shortens latency to sleep onset and increases duration of sleep in free moving crab-eating macaques at 0.03 and 0.3 mg/kg; accelerates reentrainment of circadian rhythm in rats at 0.1 and 1 mg/kg,