Oddly, I find the "little" noises most bothersome, especially when RV'ing in a campground. Just as you begin to drop off, there's that damn FLY over your head, flying and whacking into the window or wall....
bzzzzz - bonk! bzzzzz - bonk! bzzzzz - bonk!
Oh, and another thing: how the Hell does that ONE mosquito, in all the space of a 27 ft. 5th wheel, find that space about six inches over your ear to hover????
"Neeee-eeeeee-eeeeeee-eeeeee-eeeeee-eeeee!"
The bastard......