Let your little one recognize the daytime by opening the curtains of the house. Make the environment bright and let him know that this setup is perfect for his playtime. And when night comes, clean him up and get him ready for sleep. Close the curtains and turn the lights off, set everything to quiet so he will notice that this set up is night time and that he should be quiet at this point because everybody should be sleeping. Especially kids like him. It's also better to go sleep with him first until he fell asleep. :)