How times work overnight on new focus/DND

I wanted my do not disturb to be on until 10am this morning (Saturday morning). I went into focus and set an automation to have DND on 10pm-10am, and then I chose Saturdays. This morning I was awoken by a text at 9am, and when I checked focus, DND was off. I think the confusing thing is that it asks you to choose one day (Saturday) but the sleep DNDs cross two days, the previous night to the next morning. So if I want to sleep until 10am Saturday, do I actually need to go into Friday and choose 10pm-10am?

Thank you-