[JimboOmega]

There are all kind of things that happen seasonally that might dampen your mood (for instance people taking vacations, students being home from school, work being more/less busy, outdoor exercise options changing, etc). Your depression might not have anything to do with that and just be a random variation that happened to occur in the summer.

Most depression has nothing to do with SAD; it's merely a specific type. It's a type that has a fairly straightforward treatment, thankfully!

I often have a depressed mood in November and December when the sun is at its lowest, but my family also likes to make "the holidays" as miserable an experience as possible, so it's really no surprise and probably unrelated to light levels.

[majewsky]

FWIW, I have the same symptoms in winter, but none of the reasons you list apply to me. I can easily see SAD being caused by lack of natural light, and I try to spend as much time as possible in sunlight (which is hard given a normal work schedule).