My colleague and I will arrive in Guangzhou airport at 12:10am from an international flight.

Since our next flight (domestic) is at 06:20am of the same day, we were thinking of just paying to stay at an airport lounge since the transit time is just around 6hrs (too short and kind of a hassle for a hotel stay).
Does anyone know where in the airport we can stay at this time? I've read that most airport lounges close at 9:30; one lounge which closes the latest is at around 2:30am. If the lounges are already closed on our arrival, is there anywhere in the airport feasible for a rest/sleep?