The content of a dream can affect your waking life

Had a couple of weird dreams last night. Why is it that when the content of a dream is particularly disturbing it carries over to when you are awake? I know dreams are just your mind's way of sorting through thoughts and feelings and yet they can be so real and vivid. When the dream involves the people in your life and if they make you unhappy in the dream, it is very hard to shake that feeling upon awakening. Though if you examine the dream more closely, you realize there are inconsistencies in the content and thus the reality of it is suspect. Of course if you try to analyze the dream your mind can play tricks on you also. A dream is not a foreteller of the future, nor is it a message from a higher power. A dream is just all of the thoughts and feelings that pass through your mind sticking together in a random slide show. A dream is just a dream. That is what I keep telling my self anyway and now I will do a mental shake and put the disturbing thoughts and feelings aside. At least temporarily.