Garden Gal,
You describe depression perfectly. No energy..., I am slowly improving with my sleep down to 10 hrs a night and 1/2 to 3 hours of napping during the day.
I am currently in a downturn of the depression, normal pattern from what I have been told. So I am just trying to go day to day.

The more I try to fight the tired, I use up any energy that I may of had to keep me on top of things.
During these days I often am planning on my bedtime before I get out of bed. That is tired!
Or as I learning to say- there is time and space for everything I need- and sometime it is what it is-
Besides being more compassionate with myself, I plan something for every day to get me out of the house at least 2 weeks in advance, my friends know that if I say that it is not possible they understand. It may not help you, but you are not alone in wanting to have normal energy.