How do you know you are in Depression? How do you know the degree of it? How do you know to ask for help?

I suffer various forms of sadness from simple melancholy, to unhappiness, all the way to being consumed by the dark cloud extreme.

I ask because I feel myself beginning the long deep drop.

I have had a few triggers this week that have really brought me down. I have an awareness this time around however. There has been goodness in my life and more to come which should be causing some happiness and excitement. As I said elsewhere I instead just don't seem to care.