That sounds like an unusual and interesting approach. At age 60 (in a couple of weeks) I know my ways are pretty set and I won't be attempting any of the experiments you are making.

I do think that many of those people all over the world who sleep without sleeping pads often use substitutes, such as fleeces (the original ones from sheep) or rugs, blankets, grasses, corn cob mattresses, or other types of padding or insulation whenever they can. It's not just a matter of luxury. Sleeping directly on the ground can rob your body of warmth and be dangerous any time other than high summer. Shivering doesn't lead to a good night's sleep, but rather is the first step toward hypothermia.