GHB:

Gamma-hydroxybutyrate (GHB), is the only medication specifically indicated for cataplexy. Gamma-hydroxybutyrate has also been shown to reduce symptoms of EDS associated with narcolepsy. While the exact mechanism of action is unknown, GHB is thought to improve the quality of nocturnal sleep. It works by inducing a deeper sleep and that is thought to help reduce symtpoms of narcolepsy.  It is generally sold under the product name: Xyrem.