Whenever we are in bed, he will always take the side that is closest to the door. That's the only thing that's consistent when we're laying in bed. The bed can be in any part of the room, the dresser can be on one side, the window can be anywhere, it's just the door. We actually switch sides in different bedrooms to accomodate this.
It took me a year and a half, and 5 different beds, to realize that we do this.