Opening Hours and Sleeping
CDG airport is open 24 hours, in the sense that you can stay inside, be it landside or airside, for 24 hours. The airport facilities however do not operate 24 hours. The opening hours of most shops and lounges seem to be between 06:30 and 23:00, some lounges have shorter opening hours and others push 06:00 to 23:30. The EasyCDG website has a page on lounges, and one on shopping facilities, on which you can find more detailed information on opening hours.
Incidentally, terminal 2E seems to be one of the best in which to sleep, according to various reviews on SleepingInAirports. It therefore seems that you are in luck.
As you noted, there is a Sheraton Hotel at CDG. However the terminal is landside, between terminals 2E/F and 2C/D. More precisely, the hotel is on top of the RER/Train station at CDG. You'll therefore need to exit the airside portion of terminal 2E, and walk a couple hundred meters towards the station to access the hotel.
Go See Paris, Man
Having said all of this, with a 23-hour layover in CDG I would not hesitate to exit the terminal and go for a stroll in Paris. If you are wondering how long it will take you to get into Paris, we have an excellent question on airport transfer on TSE. Moreover, here is another question with a sample quick-visit into Paris, covering Notre-Dame cathedral and Hotel de Ville.