Mahmoud Ahmadinejad can't take it anymore.

He's felled by "exhaustion."

What does it usually mean when we hear that someone is suffering from "exhaustion"?

ADDED: Here's an AskMetafilter thread that begins with the question "What does it mean to be 'hospitalized for exhaustion'? What do they do to you in the hospital, besides let you sleep?" Most of the commenters assume, as I would that it's a polite way of saying that the person is getting treatment for depression or a drug/alcohol problem. But a couple people write about personal experiences that make "exhaustion" sound like more than a code word.