i’ve found that screwing around with things you wouldn’t normally do can tend to cause nightmares
because
a) it’s a new experience, there is apprehension there, just a little bit of nervousness can spark a nightmare if you don’t realize what you are feeling and try and make sure it isn’t integrated into dream.
b) I think maybe the subconscious gets a little angry when you take over some of it’s duties that it’s been doing forever.
I mean like my dream about my grandma, now granted prior to that, I found myself impaled with a few needles and whatnot, so I was not becoming lucid in a “pleasant” dream envrionment per se… and I had all those not too unpleasant memories there…
But you know, I was going to go off on my merry little way after finding the empty box, which would generally be what I do, I tend to not poke and prod the dream envrionment, but rather just wander around or create my own…
Instead I suddenly went back and yelled “What does this mean???” and… I got an “answer” all right, not one that made any damn sense though… but it was a bit scary for me, even being lucid, to have some demonic zombie like looking version of my grandma whisper in my ear.
So I don’t know, it was like it was mad that I asked, either because I should already know (implied by “you tell me what it means”) or because I was snooping into things originally fairly isolated to my subconscious, that I don’t usually invade.
that and I figured it wasn’t a good symbol before I asked.
oh and, I think lucidity related nightmares tend to involve rather important issues that you are neglecting or over looking, such as phobias you need to get rid of (in a dream is the ideal environment) or things you are repressing etc… it’s like now that you are lucid you are more likely to remember things and pay attention, so you can be sent a lot stronger than usual signals, perhaps.