Hey, yep it was a Yogi bear ref, I'm dyslexic so only tend to half read 75% of the actuall words I look at (this also explains why my typing and spelling is somewhat erratic at times) so I tend to read things how they look at a glance so many forum names are misread in my head
I tottaly get the black days or weeks, I've just had a couple of days of being an ablolute miserable c**t, don't know why, but then I ate nothing all day (my mind said wha't the point in eating you'll only get hungry again, which had been part of what was stressing me)and in evening ate lots and lots and lots of sugary crap - gluten free triple chocolate cookies, coconut macaroons, galaxy bar, maltesers and almost a whole packet of jordans contry crisp ceral (that's half a fecking kilo

)
I then felt slightly better and decided I probably need to eat more carbs all the time to stop binging, I think for me low carb + stress = constant hunger; massive crash and sugar binge. mod carb + stess = copable just.
Can't really coment on the sleep as it's been 4 years since I had a decent period of good sleep (4 year old who only just started sleeping when next one came along who is the lightest nighttime sleeper ever).
But I do know that this lack of sleep is causing me stress, and making me a grumpy bugger, and that is not helping me keep things in perspective, which means I'm more likely to go into a down.
So I do agree that sorting your sleep out could be a good start to getting out of this cycle. I assume you have tried all the normal stuff, white noise at night, very dark room, cut out blue light before bed, eating something carby before bed.
I would also recommend self hypnosis for sleep if you haven't tried it, we did hypno-birthing for the births of the childerbeasts and we used to listen to the CD before bed, there were times when neither of us could remember anything past the first relaxation bit (less than 2 mins in) and we always slept well afterwards (baring being worken by the older one this time) Maybe having something carby before bed and hypnoing would see you through the night and stop either mid-night waking for snacks or 5 am waking to start doing stuff
Not sure waht else I can say to help other than I know how you feel, and it does suck, you've already said you don't berate yourslef for feeling down anymore and I think theat is one of the most positive things you can do.
I think that depressive or manic tendancies are something that those of us who have then just have to learn to embrace as part of themselves, you will never be the same as someone who dosn't get these mood swings and they will never understand how pointless it all feels when you are down. That tendancy will always be there, you learn to manage it in a way that works for you.