What do you think about when you're going to sleep?

I was laying there thinking while trying to go to sleep, and I began to wonder what others thought about. Problems? The day? Tomorrow?

Once I lay down and my brain begins an all out sprint. I've had times I feel like I'm starting to dream before I fall asleep where my thoughts make no sense.

EDIT: Also, during the day, are people always thinking? I wonder when I'm walking what everyone thinks about. Not so much about me but in general, does anyone blank their minds? I'm able to simply not think at night if I try but never during the day, even tho I've never tried.