I'm with you Kat, I've always been worried about ds getting too hot. Now even at 19 months I'm sure he is cold more often than hot (or just right!). I have him in a sleepsuit and a 2.5 tog grobag. I found that the instructions that come with the grobag suggested he wear even less, but that the mothercare catalogue suggests quite a bit more. So I haven't a clue, but do worry about him getting too hot, and even when I am sure he is waking due to being cold I am reluctant to over dress him.
Fidelma