Orexin
Orexin is the common name given to a pair of hormones discovered in rat brains by Masashi Yanagisawa at a Howard Hughes Medical Institute-funded lab at the University of Texas.Orexin has been found to have great importance in the study of appetite and sleep, specifically narcolepsy. When the body wakes up, orexin is distributed throughout the brain from hypothalamus, and when we go to sleep, the orexin levels fade and leave the brain.
The research on orexin is still in an early phase.