Our rooms aren't heated at night, so in winter, it gets cold. Maybe some blankets on top?
I did that for my first two, but Miss A is the worst blanket kicker I've ever seen so I put her in all in ones (with socks as well if really cold), single, body suit or whatever was required underneath, and then a lovely grandma knitted wool cardigan over the top (over the top of the bag too). Was much more convenient, and and I knew that no matter what she did, she would stay warm all over. She coslept with us too, so I just lay her on top of the doona next to me.

Now that its gone the other way, she's frequently in just a muslin bag with only a nappy on.