Whenever we go camping, we put down a tarp before we put up a tent. It has ever been thus, but some don't. The tarp down provides not only a layer of insulation but a layer of protection from whatever sticks or rocks we may have missed when clearing an area for the tent.
Yes, I know tents have a tarp like floor in them. Sticks don't care what you read on the box! They just cut your floor and leave you patching and mending when you could have protected your investment with a tarp on the ground. It's easy to lay down the tarp and erect the tent. If you have one of those tents that is not a square or rectangle, just fold the tarp under at the points where you need to plant stakes. If you are expecting a downpour, you can put the tarp inside the tent. It won't protect the floor but it can keep your bedding dry if you get heavy rains for long periods.
Once, when I was setting up my personal tent, a man, let's call him a gentleman as he was genuinely trying to be helpful, told me I didn't need to put down a tarp with that brand new tent. I just smiled and put down the tarp anyway. That gentleman got up the next morning mumbling as he had to dry out his bedding then patch the floor of his tent that didn't 'need' a tarp under.
It rained a little that night, but hours after it stopped, the water seeped under the tent, found the slit in the floor and soaked his bedding. I made breakfast and took him a cup of coffee. He never spoke. By using that tarp which until it has been cut, ripped and recycled, my personal tent is in like new condition twelve years later.
If you need additional insulation or back support for a shelter, all the survival guides and scout manuals suggest using vegetation in area. Leaves, moss and sod are great for this purpose, but, they are also full of sticks, bugs, fleas, ticks, ants, spiders, fungus, feces, or urine. Where do you think those bears go in the woods? Lay it down, go ahead and use it, then put a protective layer of plastic, tarp or layers of newsprint over it.
notice the tarp under?
As kids running around in the summer heat not knowing about proper hydration, we would fall into a pile on the lawn and stare at the clouds. If you are ever overheated, lie down in the grass and your body temperature will drop. I still do it. When I am outside gardening and I feel I've over done it or just feel I've done enough, I lie down in the grass. My body temperature comes down. I relax. I look at the clouds. I get up and go get some lemonade.