Totally normal. Dreams are very interesting things. You can influence their content using a number of techniques, and sometimes you do these things without even realizing it. What I bet might have happened was that you were thinking about or seeing
SH right before you fell into full unconsciousness. It is easy, for example, to dream about your favorite movie when you fall asleep watching it.
I'm not so sure I can help with the negative effects once you wake up. Sometimes, you just can't avoid scary or sad dreams. I just cry it out for a few minutes once I wake up. After that, I usually do a lot better dealing with it later on in the day.