My six year old has sporadic night terrors. They're so horrible. He hits, kicks, screams, and cries in terror but all…

My six year old has sporadic night terrors. They're so horrible. He hits, kicks, screams, and cries in terror but all during his sleep. He even has opened his eyes and stares blankly at you, but is still asleep. Sometimes they last 20 minutes, sometimes just a couple. And once he snaps out of it, he has no knowledge of any bad dreams or any sort of dreams at all. I've spoken to his doctor and there's really nothing they can do. I'm unsure what's triggering these. Has any mommas experienced night terrors like these?!