Depending on how detailed the dreams are, I'd say it's either something a spirit is trying to teach you or a past life regression. Normally, the dreams/memories are trying to teach you something or show you something. Sometimes, they're even there to help you develop a skill or aide in the workings of a story, if you're of a literary bent!
My advice would be don't obsess over them, but don't ignore them either. Write them down in a dedicated journal, with as much detail as you can as soon as you wake up. After a day or two, go back and read over the entries with a fresh view to try and see what it might be trying to show or teach you. Light meditation to draw forth clarification or ask your guides wouldn't be a bad idea, but trying to do a regression for more details without someone to pull you back is tricky and sometimes dangerous. As with anything that involves spiritual working, you could get in over your head and have trouble coming back to now.
On the chance it's a spirit wanting to show/teach you something, meditating with the intent to ask them to clarify while in some sort of protected space wouldn't be a bad idea. As long as you have protection from something negative or harmful.
I've never really researched this in depth, despite having memories and dreams surfacing enough that I'm actually using them as the basis for two different stories. Others on the Library might be able to refer you to some books on the subject.
You say "Witch" like it's a bad thing!