Just what it says on the tin. I can't recall if it's the DP Zealots or the Sentinels, but one of them fires a sleep dart. With (the Empath spell) awaken up, I'll get multiple messages that it's broken the sleep ("You serenely open your eyes") but the sleep state is not actually broken.
This sleep is a bit weird in that you have to type WAKE to start to wake up again, which is also not the greatest experience.
--