Does the radio ever stop?

This may sound like a very obvious question, but I am curious. Does the radio like KiisFm stop at a certain time at night? certainly the announcers like Ryan Seacrest cannot stay announcing forever with only comercial breaks. Do they get different announcers at night? How do they do this... because i have heard the radio as early as 7:30 am and as late as 10:30 pm