IMO, they should not have stayed past noon AT THE LATEST.
I had a casual friend from work who went out with our group a few summers ago. She got rip roaring wrecked and we wouldn't let her drive home, and made her stay at my house.
I got up the next morning around 8, went to the gym, went to get bagels, came home, made coffee, showered, etc. She WOKE UP at around 2:30-3:00 and then had to nerve to ask if I had any coffee. Ummm, yeah...about 4 hours ago. She hung out until about 4:00 before she left.
We've never gone out with her again. I did invite her over last Memorial Day, but I told her laughingly "no sleeping over" -- she didn't come.