encouraging/forcing dreams

I don't normally dream, when I do normally it's nightmares (but it rarely happens anyways, maybe 3 times a year I dream at all).

Is there anything I can do to encourage myself to dream, or force dreaming. I can't seem to figure out what specific circumstances are different when I end up dreaming, but any suggestions on how to make it happen more often or be "better" dreams when it does happen would be amazing