orexin
Orexin is a neurotransmitter (chemical messenger) that plays a role in your:
Sleep-wake regulation (control)
Feeling awake during the daytime
Appetite
Energy levels
Reward systems
Thinking
Mood
People who have narcolepsy type 1 have low orexin in their cerebrospinal fluid (CSF). Orexin is also called hypocretin.
Synonyms:
hypocretin