There are many ways to show the passing of time without once cutting away. How about: Kratos goes to sleep, camera pans up to the window, we see darkness with stars shifting across the skyline, sun then rises, camera pans back down to Kratos. Job done.
You will watch Kratos sleep 8h and probably more than once, it will be very immersive ;)
Everything they have shown and talked about God of War have looked pretty impressive and I think Sony has something big on their hands with this title.