I would get a physical and blood panel work up to rule out a medical condition. I am hypothyroid and have Hashimoto's and right now I'm in a "flare" and I feel like a zombie. I am tired all the time, I feel drugged, and I just don't have energy to do anything, yet I'm getting plenty of sleep. So I'm not saying it's your thyroid, but lots of underlying conditions can just wipe us out.