I don't have nightmares that often. Like maybe twice a year, if that. Does it qualify as a nightmare if it's got lots of scary elements, but doesn't actually scare you? My nightmares do that: lots of gross/scary/disturbing stuff, but I'm never actually all that frightened. Half the time I wake up with, "That was so cool! I gotta write that down!"
The last time I had a nightmare that really disturbed me was maybe three years ago. It's pretty gross, so the rest will be whited out for the squeamish. I dreamed that the police or somebody, I was never clear who, had decided that the man lying in my father's grave was not actually my father. So they exhumed him. But instead of taking him to the coroner's office, they put the coffin down in the middle of my dining room table. When they opened it up, instead of seeing bones, or my dad, it was full of that melted adipose soup you read about.
That woke me up out of a sound sleep, and I didn't sleep again for the rest of the night.
