My friend keep having nightmares about her past. What can she do to stop them?

I love dream physchology but I can't seem to figure this out. My friend has flashback dreams of her childhood. She very open with her past, she doesnt try to bare all her past in her, when she feels bad she admits to it and goes on with her day. Usually these type of dreams occur because the person fails to realize the actual damage of what it has done to them and bottles it inside. She say's she can't forget these memories and dreams, that its very vivid to her and she feels it as if it were yesterday. I've asked her to write down some of these dreams and memories that way she would never feel like she'd forget them and have them right there and maybe she'd feel free to slip away alittle but she has tried that and she said it doesnt stop the nightmares. What should she do?