I don't worry about bugs crawling into my mouth while I'm sleeping, and I know that the whole "people eat 7 spiders a year while they're sleeping" thing is bogus, but I do worry about bugs getting in other places. Bugs have gotten up my nose, which isn't too hard to deal with. They've gotten in my eyes, which is harder to deal with and is very unpleasant. I also had a bug crawl into my ear while I was sleeping once. A very disconcerting experience to say the least, and one I would not like to repeat.