I've slept on a carpeted floor for decades, zero back issues. Just one night sleeping on a conventional mattress leaves me with weird back pains and a stiff ne

I've slept on a carpeted floor for decades, zero back issues. Just one night sleeping on a conventional mattress leaves me with weird back pains and a stiff neck. Not only are they costly and a PITA to move, mattresses waste a lot of space too. Traditional Japanese tatami mats are basically the same thing in terms of flatness and hardness, they're not known for having sleep/back troubles.