Thread: Sort of a technical question, I suppose.

So earlier today I was driving home from the mall when my mind started to wander to things other than driving. Then, when I got to a stop light I fell straight into a mini-dream/nap thing until the car behind me honked and I startled out of it and went on my way. The odd thing about the whole thing was that I couldn't even vaguely remember what I dreamed about in those few seconds - though I'm completely positive I was in a dream state and had some sort of dream - even immediately afterwards.

My question is then, why does that sort of thing happen anyway? Why does our mind just instantly erase all those memories of dreams? It's always bothered me that we automatically forget what's in our heads for that whole half of life that we're sleeping...