Sometimes when I awaken in the morning, even if I can't necessarily remember any of my dreams or if I even had dreams, I'll have a clear image in my mind for a second or so. The first thing I think of each morning would be an interesting fact to record and catalog, except most of the time my mind is far too mushy for an hour or two upon waking up to actually remember to do anything like that.
But I do remember the first image that came to mind this morning. This morning, the very first thing I thought about after waking up was... one of the cashier girls from my building's cafeteria, and the guy who runs the grill. They were leaving about the same time I did on Friday, around 9:00, and I ran into them getting into the elevator as I was getting out of it. I have no idea why that image would have been the first one in my mind this morning.