It's kind of a weird one. Originally it was an antiseizure med. Now it's used to treat migraines, sleep walking and some other sleep issues (seen it used for ptsd nightmares), and bipolar disorder. Doctors like to prescribe this one. My boyfriend, my dad, and I have all been on it at one time or another. Didn't do a anything for my migraines but my dad swears by it for his nightmares.