Any time I hear an unusual noise whilst sleeping, I leap from bed with my dukes up a moment or two before I wake up. So far I haven't punched anyone, thankfully, because it's usually my wife just going to the bathroom.
Our plan goes like what others have said: I go investigate/buy some time while my wife gets the kids out. If I don't join her in a minute, she calls the cops. It ain't perfect, but it's what we got.
My weapon of choice is a 23-oz framer's hammer. I call her Mjolnir. (normal framing hammer's about 16 oz.) She's always on my person.