Maybe i'm right, maybe i'm wrong. But i seem to remember something along the lines that when the first knockout wears off (ie: if it's blackjack) You can wake up, but if you go back to sleep, you won't be waking up anytime soon.(Because of bard sleep)

I guess what i'm trying to say, is i don't think it stacks and you got a little spooked by your affects list.

Now as to your poison thief thing, i have no idea about that one.

Cheers.
Jhyrb.