It is made of small pieces of woven split bamboo that help to lower body temperature and improve comfort during sleep.
[5] However, in the late 1990s and early 2000s, as more modern foam beds developed, and air-conditioners became more common as a cooling method,[6] the popularity of mahjong bamboo mats dropped significantly.
In China, mahjong mats are usually bought at cheap prices at the beginning of the summer and are thrown away as garbage at the end of the hot season as they are slept on directly.
The large specific heat capacity means a specific object can help heat to be absorbed, so if the initial temperature of the mat is lower than the human body surface temperature, sleeping on the bamboo mat will feel cooler.
[10] However, mahjong mats also have poor air permeability, high hardness, and they tend to break easily when the bedding is uneven.