Night terrors/seizures?

One of my friends recently started doing really weird things in her sleep. Almost every night (i've witnessed it) she'll scream or wail or make some weird noise and then have a seizure..or something like a seizure..and sometimes she'll "wake up" and have a conversation with you and then fall asleep and never recall it ever happened. Once she came into school with her face all bruised up and scratched (she wasn't abused) because she fell out of her bed while she was having a seizure i'm guessing. Does anyone know if someone that has night terrors or something like i explained, can hurt someone..is it common with people with these disorders?