My grandma also had a nightmare last night, and woke up screaming. She is blind and stuff.
She was locked in a refridgerator, and couldn't get out. (That doesn't even make sense, but my Grandma is getting old, and it was a dream.)
I had to calm her down, convince her she wasn't in a dream, and I had to talk to her for 3 hours because she didn't want to go back to sleep. :P