Hi, what your friend seems to be experiencing is called 'night terrors'. She should visit a psychiatrist as an anti-anxiety drug could help her stay calm. Secondly, for the time being, she can try to keep a journal where she note down her dreams when she wakes up as it could help as a sort of ventilation source. She might be experiencing these nightmares due to negative thoughts or fears that could be residing in her unconscious mind. So it is important that she be in a happier and calmer state of mind before going to sleep. She could try listening to some soothing music at just a low but audible level and drift off to sleep (don't bother to switch off the music, let it play through the night).