Is it okay to let my 10 week old baby sleep on his tummy during the day if he falls asleep like it? I do tummy time with him and on the odd occasion he will end up falling asleep on his tummy on his play mat. Is it okay to leave him like this as long as I am watching him? I don't want to move him as he will not sleep then for another few hours and he becomes really cranky and over tired. I am aware of SIDS and I would never do it during the night I am only talking about leaving him like it during the day while I am awake and watching him.