Where to sleep inside public areas of Terminal 3 and Terminal 2 of Beijing Capital Airport?

I am thinking of booking a Cathay Dragon 3.30 am flight to Hong Kong from PEK Terminal 3 or a Hong Kong Airlines flight to Hong Kong from PEK Terminal 2 at 7 am plus. Where can I sleep in the public areas of these Terminals? I have spent too much on accommodation at Cordis PEK Airport Hotel for three nights.