Sodium oxybate (brand name Xyrem, as well as Xywav with added magnesium, potassium, and calcium) is a central nervous system depressant primarily prescribed for the treatment of cataplexy and excessive daytime sleepiness in patients with narcolepsy. Chemically, it is the sodium salt of gamma-hydroxybutyric acid (GHB)—a substance known for its historical use as both an anesthetic and, illicitly, as a "date rape drug."