Hi, Sarah -
I have suffered it too, although not 6 months worth (OMG!), but a good 6 weeks I lay in my bed, to weak to bathe, go to the toilet, much less do ANYTHING around the house. I was totally worthless. And the funny thing is, I wasn't depressed like sad or anthing - when it started.
Leaden paralysis is unique to bipolar depression, it doesn't happen to clinically depressed patients. What happens is the voluntary movement of the body is kind of shut down, what controls thinking and voluntary movement, while the autotomic system (that controls breathing, heartbeat, etc.) is fine. No wonder we can't MOVE! Thus the term "paralysis". That is bipolar depression. It's not crying and feeling sad necessarily, but the psychomotor slowing. But you can bet after a week or so of that crap I was plenty darned depressed! And so angry that I wanted to do, needed to do things, but physically couldn't. Try telling somebody else that. They think you're feeling sorry for yourself and just don't "feel" like getting out of bed. Nobody understands that, even many pdocs don't know about it. Fatigue is fatigue to most people, this goes way beyond that.
The only thing that can help is good meds, I highly recommend that everyone who can take it, take Lamictal, it's a mood stabilizer, but more for the down part. The only med that can stop you from going DOWN. I would have been in bed already this time of year, but Lam has so far avoided it. Some days I feel my body slowing and I'm terrified it will happen, but the next day or two I'm ok again.
This is the time of year we all cycle quickly and most of us experience some depression due to lack of light, that's where the lightboxes come in, they are a little costly, but worth it if you can swing it. Get as much sunshine as you possibly can, sit outside and read if you can, not too cold, I won't tell you to take a walk if you can't, because exercise doesn't give you more energy when you're suffering from it, only drains you and you can't walk anyway when it gets bad.