After going into detail about SAD, and now being comfortably back from it, in retrospect I see that it was a good thing to go consciously through that whole process in wide-awake observant detail; in retrospect it looks like it was just a simple mental molt, something that needn't have too big a deal made over it in the future. In me, like in many other kinds of mammals, it seems to be a light dependent or seasonal molt.
All sorts of animals - insects and birds and reptiles and even monkeys and apes molt: why should we humans not have the pleasure? Just because we no longer have a fluffy pelt? It's something that can be ignored but why would we want to do that if we are trying to learn to live in harmony with our own deep rhythms?
Like many other things we humans have sublimated or evolved new strategies for, our molting is now experienced mainly at a symbolic level, I suppose. It may feel intense at the time, and confusing, but like any other sort of molt, SAD leaves the human organism renewed with a shiny fresh mental coat, fewer mental parasites attached, more room to breathe, more comfortable emotionally. There will always be a sense of vulnerability associated, and some raw emotional processing to do, but really, it's necessary once in awhile, and it sure feels good once it's over with.