I started having nightmares at the age of 4. But my life was the kind where I hit the ground running pretty much. My nightmares have never been about anything real, so it stumped my therapist. I had all manner of nightmares then. Like
@seedling, sometimes they were normal and built up into something bad. Sometimes I could semi-lucid dream and see that an area went to a "bad" place so I could walk away from it. But most of my nightmares played out as horror action movies, in chronological order. I'm talking epic aerial battles with epic super powers fighting epic monsters, or trying to escape epic disasters. (Apparently, my brain likes epic.) I've actually written a lot of them down because they'd make amazing disaster movies.
Then I had a life-threatening illness, got medication for that, and the way I dream now is completely different. I don't remember them anymore except for distant fragments that I quickly lose after I've been up long enough.
I had a series of events recently that sparked a relapse. I didn't know it since I'm already so used to managing my symptoms on a daily basis. But after the last event that sparked panic, I had 3 nights of nightmares, again nothing about what really happened. I still only remembered fragments, but I vividly remembered those fragments with strong attachments of emotion: anger, frustration, extremely aggressive (I am never like this in my waking world). I still remember them over a week later.
The nightmares were actually the thing that caused me to start paying attention to my emotional state and ultimately brought me here.