My DS is about to out grow his 12-18mo sleepbags. He has a little pillow so I would love to buy him a duvet but he HATES our duvet when he ends up in our bed. I really dont want to fork out for a new set of sleep bags at his age. I have been putting a blanket over him once he falls asleep for naps but ideally would like to just put him to bed at night with a blanket first time. Second issue is hes so damn wriggly I cant imagine he would stay under the blanket for more than 10min. So wont he get cold? Any suggestions to transition out of the bags