I can vouch for it that dreaming people can affect liminal space. Sabetha told me it happened way back before I ever got here, that people's dreams started shaping liminal, and it happened to me too--except it was more that I was on a vision quest kind of thing--but those are basically waking dreams, so same difference. Anyway, my vision-quest totally changed all the liminal space around me and even sort of reached out to my friends--and then when it was all over, everything was kind of blank around me. Like liminal space when Jules broke it. Except brighter.

I guess that means dungeons are sort of physical nightmares. Maybe if you can tell you're in one that makes you a lucid dreamer.