Don't you love it when you're reading and then you suddenly have an epiphany?
Two years ago I had severe depression, and when I was coming out of it I started hurting myself. I later realized that what I did was only minor, I didn't actually cut myself (I didn't want to deal with the blood) but I did cause myself pain by pinching myself really hard and doing other little things like that. Nothing serious, but very intentional and very unpleasant.
Afterwards, and even as I did it, I wondered: why? Why in the world?
It seemed like a way to physically express what was going on inside of me. Yet that didn't seem to fully explain it, and I've wondered about it.
Then, I found this passage in Songmaster by Orson Scott Card:
"...and he rubbed his face back and forth against the wood, and threw himself to the stone floor, so the pain would drive all the other voices out of his mind, would let him hear the one voice he searched for, because that was the voice that would save him from the terror that swam every moment closer to the surface where he watched and waited helplessly."
I was listening to the audiobook at work and actually stopped what I was doing for a few seconds as this sunk in, and as I compared it to how I felt.
In Songmaster the pain is used as a release. Maybe not intentionally, not with the character saying "Oh, I'm going to hurt myself and allow my frustrations out that way, so that it will help me heal!" But that's what it happened. And it occurs to me that I started hurting myself when I was recovering. Maybe it was part of the healing process?
NOTE: I have not properly researched this. This is only my own thoughts on the matter, trying to make sense of my actions two years after the fact. I would not recommend hurting yourself as a cure for depression. If you're depressed I highly recommend that you do what I refused to do at that point in my depression, and get help.