I don't consider my "bad" dreams "Nightmares". I've had vivid dreams in which I've seen the people I love die, and I've had dreams in which I've killed people myself. Most of my dreams are morbid or unsettling. What is weird is that my dreams genuinely feel more real than "reality". I have all the relevant emotions (in real life I've concluded I have three emotions, while I "have" other emotions, they manifest themselves in purely physical ways, for example I don't know I'm scared but I'm shaking), and despite the madness and in-cohesion of my dreams, they feel "right". My sad dreams feel appropriate, as do my happy and violent ones. I wish I could feel like that in real life.
My unsettling dreams are terribly uncomfortable, but they are a great experience. I get the "schitzophrenic" emotion, as I've dubbed it. It's an odd feeling, an overwhelming sense of...oddness, of wtf?. It's a little indescribable, it's a total lack of comprehension. This video made me feel it when I saw it first. The emotion is very similar to the emotion some aspies and auties get when something "changes"
[youtube]http://www.youtube.com/watch?v=vXyIB2L52Dc&feature=channel_page[/youtube]
But all in all, I love dreaming, I look forward to every type of dream.