There isn't a whole lot of research on dreams. Matthew walker at berkeley has a theory that your dreams are your way of working out things that you have a lot of emotion about, and actually kind of self administer exposure therapy. I've always assumed the reason so many of us dream about things that make us scared or anxious is because we don't want to deal with them while conscious. When i read about one function that dreams are meant to accomplish, it is this sort of flushing the toxins. But it reminds me of stephen king. He once spent a little bit of time with him, and that was the reason he said that he writes, to get rid of those