I have some friends with the annoying habit of texting me at 1am on every drinking holiday. Because of the nature of my job, I keep my ringer turned all the way up. But when I get a loud text alert in the wee hours, it scares the snot out of me. Is there an app to automatically turn my ringer volume down between certain hours? I've searched all over the app store, and there doesn't appear to be "an app for that".