My depression gets worse in the summer, not really SAD... for me, it took a bit to figure out why. Finally it clicked that I had a significant trauma that occurred over the summer between 11th and 12th grade. Somehow, my brain correlated the trauma to the season. The change in weather (it gets really hot where I live starting May and June) and also the longer days (I have also become a night owl, less people, less anxiety) trigger my depression. What made it click was when I realized that the depression started to subside around September, which is homecoming for high schools here normally. Pretty much as soon as I started seeing mums at the grocery store floral area, I started feeling better. That detail was significant to the end of the trauma.

I'm not trying to say you don't have SAD, but just trying to point out that there may be some off the wall explanation for the depression.

Puck