Normally I'm very neat and organized but, when I get depressed I set stuff down in places were it doesn't really belong and leave it for a while or even go a long time without cleaning up a messy room and if it's bad depression then, seeing the mess makes me feel even worse so I just leave that room so, that I don't have to look at it.
Eventually, when the depression passes and I'm disgusted with the mess, I clean it up again.