The cycles in depression can feel so incredibly cruel. It's like you just can't trust feeling better, which can feel depressing in itself. I feel for you so very much as you face the challenging cycles of depression.
Personally, I'm a self questioner. This is partly how I manage staying out of depression. I'm a sensitive gal so I'm prone to really feeling the downs and know I have to be careful in how I consciously manage not staying in them. I've learned to question everything I say and do. With 'say', this includes internal dialogue. As you'd know, internal dialogue can get pretty brutal. I left 15 years of depression behind me some time ago and there have been a poop load of questions since then :)
I'll share my own most mind altering life changing epiphany in the hope that it makes some difference and possibly helps you spot what's going on in the cycles. Challenges in life are never ending. You can always feel when you're in a new one or one that has come 'round in a repeating fashion. If you can't identify or resolve a challenge, the nature of it may be to bring you down until you work out what it's about. Once you work it out, you go up a level. It's like you graduate to a slightly higher level of consciousness or self awareness. Some challenges may take less than a day for me to work out, some take days and some have actually taken years.
I've found some challenges to be clear and some so unclear that they've just about done my head in, leaving me entering into what feels like the beginning of a depression. I'm familiar with that feeling, so I know when I'm beginning to enter back in. I may spend hours or days meditating on what the challenge could be so as to avoid fully going back into a depression. A little obsessive but such meditation/analysis proves revealing.
One of the least clear challenges I've ever faced involves the energy factor. Why don't I have it, what's drained it, why can't I 'charge up', who's exhausting me or not energising me, where and how do I get it? The list goes on. Basically, I've learned that if I don't have enough of the right kind, I'm stuffed mentally and physically. Incoming and outgoing channels are what connects me to life. On the odd occasion, I'll actually sleep for an entire weekend just to charge up. I've learned I need it and therefor see it as highly productive, not lazy.
Could you see yourself identifying and rising through each challenge you face, as opposed to being brought down by them?