Fell asleep sitting up

I was putting my son to bed and he got up after i laid him down and was sitting up playing with a book i left in the side of the pack n play and all of a sudden he just falls over. At first i thought he fell over on accident and when he didn't move or cry right away i got scared. Then i realized he has fallen asleep sitting up qns fell forward and now i cant stop laughing. 😂😂💙💚