Even when you're depressed, you still need to eat regularly. It doesn't seem like you'd be getting a breakfast since you wake up so late.
I'm going through a fixation on staying in bed too, but lately I've been waking up earlier, and I can only guess and attribute that to me trying to balance my daily diet, getting more vitamin supplements in my system (not drugs, vitamins). I've been getting out of my house to go on long walks, and now more than a while ago, I feel like I'm using up and gaining energy from all of that exercise. It's not healthy to deprive yourself so much, but remember, even when you're in a schlump, life goes on, and that includes your own life as well.