I did read some of the Man Who Mistook His Wife for a Hat... back in high school, for a class. I don't think we read the entire thing, but it was fascinating. In my story, I want my character to be suffering from something called Cotard's Delusion, or Walking Corpse Syndrome, where they think they're ceased to exist, or that they've died.
I started writing this in 3rd last night, just in case I couldn't handle it in 1st - and I'm really not sure I could do this in 2nd, having never tried that before - but anyway, it seems to be going well. The problem is that I want there to be a twist at the end, a la 'Sixth Sense' but...if the guy is going to be talking to all sorts of people all the way through, I'm not sure it makes sense to have him turn up as dead, after all, at the end. Doesn't make sense at all. So I'm left back at square one. May need to throw out what I've written so far and start over...