Vampire Energy completely depleted, help

I noticed that too. The only way I've seen to quickly fix it is to use the needs cheat. In the cheat box, type testingcheats on, and hit enter. Then you can shift + click on any Sim and choose Cheat Need, then Make Happy, you can also disable need decay. Although I've found it randomly turns back on. Then if you want to turn the cheats off just type testingcheats off, but I always leave it on.
There doesn't seem to be any fast way to fill with regular game play, just sleeping or meditating.

Oh dear. Yeah, you really need to cheat their energy bar up, otherwise they'd just die immediately upon entering the outdoors.

Honestly, I'd just toss them into the nearest coffin instead and make sure they hibernate enough. I'm a little lazy when it comes to cheating the needs in this game. I actually haven't run into this bug recently yet, but I definitely hope they fix it again.

Although I do use cheats in my game, I only use them when necessary. In my main save game, I play Caleb Vatore, but he rarely ever needs to sleep unless he uses his powers excessively (he's an extremely hyper guy).

He never seems to sleep long in a bed, but there are certain instances that a coffin can't be used. For instance, when vacationing in Granite Falls or Selvadorada. I have found I can put him in a tent but it seems to work as hibernation. You actually have to wake him up. He will not get up on his own.

The only problem I had with this is one of the outdoor aspirations that required him to sleep in a tent for 5 nights. It never did register as he does not wake up on his own, I had to wake him so the aspiration wouldn't accept it. So yeah, I had to cheat that part of the aspiration after I made him sleep in the tent 5 consecutive nights.

C'est la vie! In this case only meaning 'That's life' with the sims.