I had never heard of diurnal mood variation, but it sounds what I've been dealing with for over three years. Horrible anxiety and dread that starts even before I'm fully awake, but usually becomes mure manageable as the day goes on. By evening I often feel fairly normal, and go to bed hopeful that the morning horrors won't come back.But they always do, to a greater or lesser extent.
I have resisted meds, but seeing that you've gotten at least partial relief, I should probably reconsider. Waking up every day in fear of my own life is,well, no way to live...