don't sleep in your day clothes they well be too damp even if you can't feel it.a total change into dry sleeping gear is hard because your putting in cold clothes.it's tempting to get into the bag in body warmed up stuff but the damp will chill you and the bag will get damp as your body uses calories to dry the clothes you wore all day.
i would suggest striping down and putting on a polyfluff sweat suit and polyfluff soxs and hat.
a bit of a snack before bed helps but stay away from drinks or you will find trying to pee in a bottle or zip lock in a sleeping bag is a looser.