I have read a very few posts on curezone relating to this phenomenon. I had a similar experience. After my early 30s I never remembered ever dreaming, however after I started changing my diet I started having little blips of something going on. Then when I started my first cleanse, a bowel and parasite cleanse, the blips were definitively some sort a dream activity. At this time, there was little that could be remembered or defined.
I started flushing in January of 2006, and the first dreams I could wake up remembering were not nightmares per se, but they were dreams of possible real-life events that would be terrifying if real. So there was a definitive nightmarish fear factor.
Over time and since then, things smoothed out a great deal. I have not had any fear inducing\nightmarish dreams for a while now.
I wonder if anyone has done some study on this... rather fascinating that as people cleanse dreaming comes up on occasion. Not something we normally talk about during our cleansing journeys. I would imagine there are many more who have noticed some sort of dreaming activity changes over the course of cleansing.