Dream a little dream

While I am an excellent sleeper - give me two minutes and I'm off - I've been having bad dreams lately which leave me feeling stressed and tired in the morning. Sometimes they're an obvious nasty one like being taken prisoner but other times it can be mundane things that I don't like or the exhaustiveness of something.
I don't know what can help to shape a better and more uplifting sort of dream - if anything but it feels like my dreams only drag me down lately. I don't even remember the last time I enjoyed a dream, even the ones with Lincoln either revolve around him morphing into different animals or being attacked.
Have you got any good suggestions?
Take care,
Sophie