Cita:Now, the Food and Drug Administration has approved the drug for a new use: treating “idiopathic hypersomnia,” a mysterious condition in which people sleep nine or more hours a day, yet never feel rested. Branded as Xywav, the medication is thought to work by giving some patients restorative sleep at night, allowing their brains to be more alert when they wake up. It is the first approved treatment for the illness.