Inside Naruto is 'yin' Kurama, and went to sleep because after busy gathering chakra for Naruto.
The Kurama outside is 'yang' Kurama, but the 'yang' Kurama will tell 'yin' Kurama inside Naruto
"Your turn to be inside Naruto, as i was inside for 17 years, torturing and demanding by Naruto...hehehe.."
"I cannot be inside Naruto, because Minato had said so, Naruto body was too small to have both inside, hahaha"