M.P.
Hi M.,
What was helpful to my children was "rewriting" the nightmare --listening to the story of their dream, then together imagining a silly/ happy (instead of scary) alternate ending. This allowed them to replay the dream, which they tend to do anyway, but to have some control over it. My kids (ages 17,20,23) still laugh about some of those crazy stories we told. Try it. Hope this helps!
M. P.