Why do Japanese and Koreans like to sleep on the floor?

Both Korea and Japan belong to Han culture countries and are deeply influenced by China's ancient culture. Clothing and architecture refer to the place of China, China. From the Han Dynasty to the Tang Dynasty, nearly 1000 years ago, almost all the land was confined to today's Central China and North China. The climate is cold and the humidity is low. Sleeping on the floor will not cause joint diseases. Beds can only be enjoyed by nobles, and ordinary people sleep directly on the ground to show the difference. During this period, China was a vassal state of the feudal state on the Korean Peninsula until the end of Qing Dynasty, which had a comprehensive influence on him. So some Korean customs can be said to be synchronized with China. Before 1200, the Korean peninsula did not have its own characters, Chinese characters were always official characters, and even their official uniforms were the same as those of the Song Dynasty. Japan is far away, and its influence is only in the degree of admiration. Therefore, although the early customs were almost the same as those in China and Han Dynasty, they later developed their own unique culture. Although China has a vast territory and different climates in the north and south, the custom of sleeping has gradually developed and diversified, so it is unnecessary to change it once you get used to it, but the custom of ordinary people sleeping on the floor has not changed.