When resting you attract all of the 'nearby' hostile mobs or there is a chance that you do, although I am not entirely sure on the chances of this happening.
I have no idea what the aggro range on it is either, but as far as I can tell it is pretty much always the entire zone. Was this what you were referring to or?
I have noticed a few occasions where nearby enemies seem to react to the sounds of a fight or dying monsters as well, at least I got the impression they did.
I could not tell you what the approximate aggro range on this was though, I am not even certain if it was a listen check that triggered these scenarios for me.