I have noticed two things: 1. Plasma packs don't provide much plasma. I think they fill the thirst bar up about 1/8th to 1/4 of the way. I don't think the plasma fruit is much better. So snacki...
I definitely agree that the plasma packs and fruit are too weak as-is. I understand that they probably want feeding from a live Sim to be the 'best' way of doing it, but right now, it's just a bit crazy, IMO, how many packs/fruits it takes to make a meal.
I've never seen any indication of a sleep requirement outside of depleted Vampiric Energy though. Thinking you may have some kind of weird glitch there.