Neuropeptides that play a significant role in the regulation of food intake and sleep-wakefulness, possibly by coordinating the complex behavioral and physiologic responses of these complementary homeostatic functions. A broader role in the homeostatic regulation of energy metabolism, autonomic function, hormonal balance and the regulation of body fluids, is also suggested. Orexin-A binds to both OX1R and OX2R with a high affinity, whereas orexin-B binds only to OX2R with a similar high affinity (By similarity). Associated with perikaryal rough endoplasmic reticulum as well as cytoplasmic large granular vesicles at synapses. Belongs to the orexin family. Qui dort dine - Issue 15 of October 2001