Orexin A vs Orexin B: Dividing the Wakefulness Work

Orexin A and B come from the same precursor and both regulate wakefulness — but they divide the work. Orexin A is fairly non-selective, hitting both OX1R and OX2R; Orexin B prefers OX2R. That difference matters because the two receptor subtypes aren't redundant: OX2R is particularly tied to sleep-wake stabilization, and narcolepsy type 1 (with orexin neuron loss) responds differently to OX1R vs OX2R manipulation.

Researchers use the pair to pull the arousal system apart — which receptor drives alertness, which drives the stability of the wake state. Members discuss how that receptor selectivity could, in principle, let a future compound tune wakefulness more precisely than the non-selective peptides.