Orexin B, also known as hypocretin-2, is one of the two orexin peptides (the other being Orexin A or hypocretin-1) produced in the brain. Orexins are neuropeptides that play a significant role in regulating sleep-wake cycles, appetite, and arousal.

Here are some key points about Orexin B:

Origin: Orexin B is produced by a small group of neurons located in the lateral hypothalamus.
Function: It plays a crucial role in promoting wakefulness and inhibiting REM (rapid eye movement) sleep.

Receptors: Orexin B primarily binds to the Orexin-2 receptor (OX2R), although it can also interact with the Orexin-1 receptor (OX1R) to a lesser extent.

Role in Disorders: Deficiencies in orexin production are linked to the sleep disorder narcolepsy, where individuals experience excessive daytime sleepiness and sudden bouts of muscle weakness.

Research: There's ongoing research into orexin receptor agonists and antagonists for potential treatments of various disorders, including insomnia.