"Yeah, I'm really having no trouble at all breathing around this pillow, chief."
This restart period varies on a case-by-case basis, but it takes the body roughly 15 seconds to use up the oxygen in the blood. After that, the clock starts ticking: A minute without breathing destroys some of your brain cells. Three minutes and you likely have serious brain damage. After 10 to 15 minutes, you're generally fucked -- unless you're one of the rare cases that survive after 40 to 60 minutes without breathing. Unless the killer has brought a sandwich and a book to read, they're better off flicking the victim to death.