If you only have 8 hours and your main interest is maximising sleep, consider the airport transit hotel:
https://www.zurich-airport.com/passe...hotel-bedrooms
I stayed for one night last August, and while it's basic (I had a windowless room with twin beds, sink in the room and
shared toilets & showers **), after a longhaul flight I slept really well and was much fresher than I expected the next morning. Bookings can only be made by email/phone.
**I bolded the shared toilets/showers as I can understand this may be a dealbreaker for some. However they were very clean when I was there.