Some dreams are too vivid, they seem real.
Some dreams shock you because you’ve never had thoughts like those in your dreams before or, at least, you’ve never thought of them consciously.
Dreams are the messages of the subconscious. They tell the story of how your mind works when you don’t realize it. Sometimes, it would turn out, that who or what you dream about in your subconscious is actually a reflection of your subconscious personality. Your subconscious personality could be very different from your conscious personality. Thus, the thoughts between the two could be polar opposites. You might not recognize your subconscious self.
But, the undeniable fact is, you are both your conscious and your subconscious. You could deny your dreams all you want, but there is still the truth that these comprise the thoughts of your subconscious and, thus, essentially comprise a part of your thoughts whether you like it or not.