I have seen you tout 'Learned Optimism' before. Had not read it though. Helpless is very much the feeling I get when she is like this. I will order the book tonight. Nice to see you stop by.
I am not sure anything triggers it. However, I can usually predict when it is coming. It's strange, the physical symptoms usually precede the emotional. For a couple of days she can be jovial, but have cold like symptoms without the cold. She will be tired with head and body aches. The sadness does not come untill a couple of days later. Truthfully, I think it is pretty much all brain chemistry for her.