When my husband and I drive through the neighborhood, one thing we often discuss is why the people here always seem to keep their shutters closed. Nearly all the houses and apartments have them on the windows, and when you look around, nearly everyone keeps them closed, all the time.
I love light. I liked the house we rented for that reason, it even had a window in the bathroom which I really wanted. I don't like to feel like I am living in a cave. So we always have our curtains pulled back, and windows are usually open as well, to let in the cool ocean breezes (well, most of the time they are cool).
I asked my neighbor why everyone keeps their shutters closed, and she said to keep bugs and dirt out. That would be a good reason, but we don't have that big of a problem with bugs, and I don't think my house is any dustier than others. She said she that cockroaches could fly (well, I googled that, and apparently they can fly, but I have never seen that). When cockroaches start flying in my windows, I will indeed close the shutters.
Another good reason would be to keep it cool inside, which I understand, as the sun heats up the house. But most of the time temperatures are in the 70's and low 80's, so even with the shutters letting in the sunshine I feel comfortable.
The sunshine is one of the greatest assets we have here in the Canary Islands. We may be the only strange ones on the block, but I am going to enjoy every minute of it!