Exposure to light in the mornings

[The Big D]

I've noticed something interesting. In the summer months, I have no problem getting up early - about 6:00 or so. In the winter, it just kills me. This is with the same roughly 7-8 hours of sleep.

The only explanation I can think of for this is that my bedroom has a large window. There are blinds, but in the summer my bedroom is in essence lighted once the sun comes up. Presumably, even though I'm asleep, I somehow pick up on this fact and wake up much more naturally and earlier.

So two questions;

1) Anyone have similar experiences?

2) Has anyone tried to do anything about it, say a light on a programmed dimmer switch that slowly turns on the mornings to achieve the same effect artificially?