New answers tagged cold-weather
Plenty of places sell sleeping bag liners. Sometimes they are designed to make the bag warmer, other times to be more absorbent. For example, Mountain Equipment co-op sells quite a few, some of which are cotton and mention "absorbency" and "comfort" in their descriptions. I don't doubt that other suppliers offer them too.
I get far too hot but like you I find that layer part of the night gets cold. My solution in temperate climates is to only ever zip the sleeping bag up halfway so the top half is left loose, that way I can pull it over me or off again without waking up. If it is a wee bit cooler you could try this technique as well as a thin sheet or blanket.
Put layers on your ground sheet: cardboard (keep it dry), bubble wrap, survival bags, or blankets will do. These will mean the tent does not lose heat to the ground.
Top 50 recent answers are included