I have the same issue, and I thought it was just me. I certainly don't work 50-60 hours/week, but I work 12 hours/day and when I get home, all I want to do is sleep. And on my days off, I'm recovering from the work week both mentally and physically. I think that depression is just the icing on top of that cake. I know that my mind would be in a better state if my place were cleaner--I hate clutter--but while I have at least a little motivation, I don't have much energy.