HCRT and narcolepsy: Conceivably, the stem cell-derived cells have to fulfill the following requirements to induce recovery from narcolepsy symptoms after transplantation: (1) higher graft survival probability; (2) release orexins in a regulated manner; (3) exhibit the molecular, morphological and electrophysiological properties of fully mature orexinergic neurons; (4) re-establish a dense, functional orexin releasing terminal network; (5) grafts have to become functionally integrated into host circuitries to restore wakefulness, for example.