As Ledauna my two losses to pks both involved sleep stacking. The first came when Yanacek blackjacked me and then while I slept knockout poisoned me. I'm not sure, but Morchata may have cold be slept me as well (trying to sleep my pets). Combined, this was enough to ensure that both of my key supplications (armor of thorns and fly) had fallen. The second came when Navarro blackjacked me and then Morchata cold be slept me. In this situation the bard was probably trying to sleep my pets, but even still I was affected as well.

Doesn't this seem a little like overkill?

Fear the H2H warrior, poison-thief, bard combination. They could probably put you to sleep and then watch you age die.