Welcome to DV!

Your nightmares are most likely related to waking-life stuff. It could be as simple as stress from school or family life. A lot of times nightmares will be extreme even when they are related to problems that don't seem like a big deal. A lot of people use dream control to fight or get rid of nightmares. I personally think it's more helpful to use your lucidity to try to understand why the nightmare is there. So once you're able to incapacitate your foes, ask them why they are giving you nightmares or what they represent. You might be surprised at the answers you get. Good luck!