In Japan, it is still common to sleep on tatami-style floors using shikibuton. There are even hotel accommodations with it (ryokan). When I was trying to decide whether I should buy a western-style bed or try out floor sleeping, I came across a lot of informative opinion pieces. I ultimately made my decision to try out the Japanese-style sleep system simply because it felt nice to. It was also very affordable, so if I didn't like it I could just buy a bed.

I will add that prior to moving here, I sat on the floor a lot during my life and have practiced yoga for over 12 years. I have awareness for my body and look for ways to passively stay in shape in case I don't have time or willpower to workout.

My perception may also be different because even though I live in Japan, I come into contact with other Westerners who sometimes display superiority complexes towards the locals' way of living. I had one acquaintance get a little pissy with me when they found out I wanted to get a floor-futon for my place. They're pretty rude towards service people whenever we go out in public and made it clear that they dislike living here. I think it was an insecurity (they're overweight) that they wouldn't be able to fit or feel comfortable sitting low, but I don't think they had a right to try to regulate how I decorated my home. They actually got upset with me for making my own space comfortable for myself :\

As humans, we are meant to walk, run, sit and stand. My home country has an obesity epidemic. Regardless of if I can find scientific evidence backing floor sitting, I have to admit that there are a lot people that I know who would have a lot of difficulty sitting on the floor and standing up immediately afterwards. TBH, a lot of them would be in pain from just sitting on the floor alone. I'm not a doctor, but I know that is probably not good.

***** TLDR. ******

Floor sleeping seems to be easier to research than floor sitting. I would strongly suggest looking to Japan or China for more information. Researching shikibuton and tatami-mat sleeping (Japanese-sleep system) could yield some results. Idk what the equivalent is for China.