My Sky Shaped Box

I read a book the other week called Heart-Shaped Box. I was intrigued by the title, which I assumed was a reference to the Nirvana song. I was sort of right, but sort of wrong too. This is fine, because it was a fantastic story.
In this book, a man is pursued by a ghost that he purchased off the internet.
In one scene the protagonist notes that the ghost is visible and dangerously active while the sun is obscured by cloud. But it cannot stand the light, and when the sun breaks through the clouds the ghost is rendered intangible and ineffective by it.
To me, this rang true as a great metaphor for Seasonal Affective Disorder (SAD). While I am by no means one of those people who jumps on the internet to self-diagnose themselves the minute they have the sniffles I have wondered for some time how much the light of the sun affects my mood, my desire to hide myself away from the world.
There are days when I feel like I am lord of all I survey. There are other days when I feel like I am lord of all I survey so long as all I survey is the inside of my house with the curtains closed and the doors locked.
Bring on the summer sun!