Selective orexin receptor antagonists. 
The orexin, or hypocretin, neuropeptides (orexin-A and orexin-B) are produced on neurons in the hypothalamus which project to key areas of the brain that control sleep-wake states, modulation of food intake, panic, anxiety, emotion, reward and addictive behaviors.  These neuropeptides exert their effects on a pair of G-protein coupled receptors termed the orexin-1 (OX1) and orexin-2 (OX2) receptors.  Emerging biology suggests the involvement of these receptors in psychiatric disorders as they are thought to play a key role in the regulation of multiple systems.  This review is intended to highlight key selective OX1 or OX2 small-molecule antagonists.