After reading everyone's replies I think I maybe letting my LO get a bit too cold, she sleeps in our room and according to the room thermometer it is 18 degrees - she is in a long sleeved vest and a 2.5 grobag - I sometimes bput a soft furry blanket on her as well but take it off when we go to bed as she pulls everything up over her head given half the chance.
Sofia normally gets really hot, but our room is 16 degrees at the moment so I'm wrapping her up more than usual.
Normally when it's 18 I have her in vest, sleepsuit and either 4 blankets or 2.5 tog bag... but she hates the bag so given up on that!