Tatami Mats are a traditional sleeping surface that originated in Japan during medieval times.
Rice straw is compressed to make a hard core. Then sea grass is woven around the core to give a flat usable surface. The traditional finishing touch is always a woven brocade that's attached along the sides.
All the elements that make a tatami mat are natural and abundant. The surface has "give" so therefore offers comfort if used for sleeping and a soft landing when used for play.
Like many ideas from Asia when introduced to the world they are adopted for different purposes. Consequently these mats are used as a play surface for all ages, yoga and probably other exercises
While the main use on this website is with low level bed frames. It seems like some customers place it on the floor and use only a duvet to make an instant bed.