S/O What determines your side?

When i'm home, I sleep on the side away from the doors closest to the windows. No clue why. 

I normally travel with my beau, and he travels a lot for work. He insists on sleeping between me and the door, 'for protection.' 

I think this is incredibly sweet and appreciate this.

However, he is 'deafer than a doornail' as we say, and I think IF someone ever tried the door, I would hear it and start hitting him to wake up, then he would freak out, scream "WTH?" (cause he's deaf, you know, so he yells EVERYTHING when he doesn't have his aids in) and start hitting back (as a reflex, not because we are violent toward each other at all), and we'd be a big, flailing sheet ball. 

I assume this would startle whoever it was trying to come in...and they would be weirded out thinking about two old fogeys doing WHATEVER it is they're doing in there, what with the screaming and all, and run away. 

So, maybe he's got the right idea after all