Would it comfort you at all if you found out you were still dreaming you just weren't remembering them? Plus if you remember your dreams you'll remember your nightmares too if you have any. Maybe prazosin doesn't reduce your nightmares it just helps you forget them? I don't know. I haven't researched it so I'm kind of talking out of my ***.

Do you wake up to an alarm clock? I find that I only remember the dreams I have when I'm between pressing the snooze button because I'm in a light sleep and it's easier to remember. If I get woken up from a deep sleep all of a sudden I usually can't remember what I was dreaming about. I think that's fairly normal (maybe).