I was thinking of this on the long train home the other day. Addiction to depression or sucidle thoughts and such.
I came to the conclusion that as silly as it sounds is those feelings actually make me feel more alive. When you take it away and you are not depressed but also not happy you just live like a zombie in comparison. The two extreme's of happiness and sadness make you addicted to that feeling over the feeling of nothingness.
Thats just my theory anyway after years of addiction. I can't be just sad, my mind takes that sadness and makes it even deeper and stronger, something more powerful running through my veins.