Keeping warm on cold nights

Winter is definitely approaching and fast! It got down to 3 degrees last night and the same is predicted again for tonight. It's not even June yet! Anyway, Jonah has been coming into my bed with me in the wee hours of the morning. I assume because he's cold. I've been waking a couple of times a night feeling cold too, but I'm obviously capable of pulling my doona up and turning my electric blanket on! I already have Ruby sleeping in my bed at the moment (shes going through a phase of not wanting to sleep by herself) so being squashed between two starfish children all night makes one very cranky and sore mummy in the morning! I grabbed a couple of pairs of fleecy all in one PJ's for Jonah in the target 40% off sale a few days ago, and some long sleeved singlets. Didn't make a difference! So here is my last ditch effort before I think about putting some kind of heating in his room. A 2.5tog bubbaroo sleeping bag. $85 and he hates it! LOL! All I've heard today is "I don't like that and I'm NOT wearing it!" Wish us luck, we haven't had a heater in his room for the last two winters after we received a $600 power bill - so really don't want to have to go down that route!