Nobody "sleeps on the ground" anymore, there are excellent insulated camping pads, these are required for any sort of cold weather. ThermaRest pretty much took over the industry for a short period in the 1980s with their self-inflating foam core air mattress. It's not often a new product takes the world by a storm like that, but it sure did.
Air mattesses (slightly under-inflated, to avoid bouncing around like a cork on the open sea) were very comfortable for camping, but offer no insulation from the cold ground. Standard cots, get the camper off the ground, but are also cold because of constant cold air circulating underneath. A good insulated sleeping/camping pad underneath you will make for a comfortable nights rest.
A lot of people (not you mind you) seem to think camping requires suffering and hardship, it just ain't so! It's a lot of work to go camping, and believe me I don't go if I'm not going to be reasonably comfortable even in extreme cold. It's actually the hot, humid nasty summer weather than bothers me the most.