unpleasant
I don't have nightmares, but I do have unpleasant dreams. I loathe them, truth be told, I'd rather have the nightmares. With my unpleasant dreams they usually lave me in some sort of bizarre mood, detached, unhappy, deflated, flattened, ill at ease, unsettled, paranoid and unsure of myself and others. They are always creepy, deflating, or grotesque.
I'd rather have the nightmares.