The Sleep of the Damned.
The only way to get any rest around here.
When severely damaged or when sustaining serious injuries to the heart (“staking”), a Vampire (including his Beast) will shut down. In this death-like immobile state, a vampire can't repair himself, but at least it doesn't get worse. Also, vampires in torpor are embarrassingly easy to handle and transport.
It is also said that sometimes very old vampires, or vampires that have completely lost their humanity, enter this state spontaneously.