DS has been able to roll front to back since 5 weeks old. He learnt the other way at around 4.5 months. He's always slept so well in his moses basket, around 8pm-6am, and we transitioned to cot around a month ago at 5.5 months. Problem is, all of a sudden he wont stop rolling on to his front and trying to pull himself up on the bars, crawl, play on his front, etc etc... but won't sleep on his front. It's taking hours to get him to fall asleep! Is this a phase he'll grow out of?