My oldest used to do this. sometimes she would wake up screaming and terrified other times just talking enough to wake me up and go check on her. When I asked the doctor said to watch what she did at night, reading, TV, even what she ate. In her case we figured it was things happening at school that she was not telling us about. Things that were bugging her. She would not remember anything at all either. We have not had an incident for about a year now. Good luck.