IMO it has to do with the chemicals in the brain... when we are not so depressed we have enough of the chemicals to keep us from being "in that black hole" and while we can read what we said, we can't really "touch" the feelings we had then. I think that's a good thing.

Yes, I call my T when I am in that swirling black mass and I don't always remember how black it was at the time. I recall when I was first injured, I made tapes of my describing the pain. I later tried to listen to them (years later) and ended up erasing them (unfortunately.) Not only did I not want to remember that intense pain, but I couldn't believe how bad I was feeling.