Understanding Device Control Time

I set my zoom rooms to turn off from 8 pm to 8 am. And off on the weekends. One of my staff told me the screen was still on and I ran a test and found that the background image is still displaying. Not much of an energy saving. I'm thinking of putting in a black image but it doesn't make sense to have controls over the screen if the background image is going to be displaying. Is there a way to put the screen and/computer to sleep when no one is in the office?