I lived in a lavvo from august 2015 to April 2016, and it was the most awesome year ever (including in terms of sleep). I had a nice setup with a platform covered with sheep skins, and two sleeping bags (it reached -15C that winter in southern Norway).

Back when I was younger (10-14) I slept outside more than half of the days of the summer. In the barn, under trees, in trees, far into the forest, often accompanied by my horse, dog and cat. The feeling of waking up outside is so nice. In the forest, the first birds in the morning waking you up, finding new places and exploring. I had capes, some of wool, one of reindeer skin, and that's all you need to be comfortable during the night. I used to ride my horse far into the forest and we would just stay there until the next day. Playing flute, doing woodworking or reading while the horse was grazing.

That period from 10-14 sounds mindblowing! Magic. I'm guessing your folks had a summer house in Norway or something - I love that you had that freedom.

Hunter gatherers supposedly sleep less and get upt before dawn, those behaviour patterns are our best bet for what the past sleeping cycles were.

Climate-wise, this applies to hot places as well. I spent a few years in upcountry subsaharan Africa. Sleeping indoors was suggested and encouraged because it made it easier to set up anti-mosquito bed nets, but actually doing so was a challenge, and virtually impossible when it was humid. Much more comfortable to lay out on a bamboo frame with a sheet and hope not to get malaria that night.

Are you seriously arguing that sleeping out in the nature, potentially with dangerous animals around you, on bear skins, with several friends (on the same bear skin?) is as comfortable as sleeping on a modern mattress in your home?

There have been studies that confirm sleeping outside results in sounder and healthier sleep.

I think about it in terms of germs. Yes, on paper it's more safe to sanitize everything, but in doing so we prohibit our ability to build defenses, and actually become less healthy.

In the same vein, maybe by sleeping on mattresses indoors all the time, we fail to build a tolerance to adverse sleeping conditions, and maybe get more sensitive to them too.

I knew of an old thai man who's face looked like he was 80 and his body looked cut and jacked. He also preferred to sleep with a thin mat on a hard tile floor with his wife in a house where there were multiple clean, usable beds to easily sleep on instead.

So if your body adjusts to it, it's definitely possible to actually prefer it.

Hard perfectly flat sleeping surfaces with just a simple blanket for warmth can stimulate the lymphatic system much like a massage can.

The worst is when you have an uneven surface, like when camping and there is a rock which even your (inflatable) roll mat cant dampen out, that makes sleep difficult.

My anecdote is that when I get migraine headaches, I have to lay down and try to sleep. I have to lay on hard ground. I can't stand being on a mattress for some reason. Maybe it's about feeling more control over the position of my body.

To me there is something deeply comforting about inertness. I hate the springyness in matresses so much I got a natural latex mattress, which I found out most people get because of allergies, but to me its like a kinetic sensory deprivation chamber- just absorbs all movement and doesn’t reflect it back.

Okay, and the sensory deprivation helps you sleep? I suppose that's generally what we're headed for. Turn off the lights. Set the temp to a certain level.

The hard ground isn't giving either, but you feel it. ;)

I also can't deal with pillows when I have a migraine. Though I can't sleep without something under my head. I usually just roll up a towel or something. As I said before, I think it's about having precise control over body position.

Like OP, some of the best nights of sleep I've had in my life have been while camping (in good weather, mind you). Different strokes maybe.

Hunter gatherers thriving on 5-7 hours aren't sleeping on modern mattresses either.

Yes.

I would love to hear more about the survival situations you did (I'm guessing intentionally) - and about the bear skins!

Not much to say there, sadly (fortunately?). I grew up north surrounded by forests and had classes. Then as a kid up until young adulthood, gathering with friends and going into the woods with minimal equipment for the weekend was the easiest way to have freedom away from the parents.

As for the skins, I have only slept on a bear's because it was at someone's cabin. Even if the place didn't have much in term of heating it was still a good night. Sleeping on the skin wasn't planned but it happened due to comfort. A friend had a beaver's and a wolf's but those are too small to sleep with unless crafted into something bigger. They did keep your knees warm however!