When you're first turned, the hunger is overwhelming. Everything is intensified. I had no idea what was even happening to me, what our parents had done to us, and we killed a lot of people because we just had no clue what was even real. It's the same for a lot of vampires when they're new and the guilt can be hard to cope with, so they turn it all off.
I've turned mine off once. In the Cage. I got Lexi'd into turning them back on.