Sleep and plasma

I've never had either of my vampires have any human needs. They don't necessarily need to sleep, but I do let them hibernate occasionally (but they might easily go more than 24 hours without any sleep). I remember also reading that someone here had a vampire who needed to use the bathroom.

I was just wondering if this bug has something to do with those vampires having been turned from humans? Because I made both of my vampires in CAS as vampires.