Should I keep my lights at 50% brightness?

The lights in my room are controlled by a dimming switch. I don’t like too much brightness, and I thought it’d save energy as well. But, when I don’t push the switch all the way to the top, there’s a slight buzzing noise. I wonder if this isn’t good. It’s not loud enough to bother me—you have to listen to hear it. I don’t know much about electricity, but maybe someone can let me know if it’s okay or not.