The beds provided privacy and convenience to the occupants and epitomized how those who could afford it enjoyed their "sleeping world."
Long ago people first slept on the floor - there was no concept of a bedroom. Where they slept could also be where they received guests.
It is still a tradition in the North China countryside for an important guest to be received on the bed. Later, people started using a low wooden couch for sleeping. It had no railing or decoration and was often used outside in the summer. Examples can be seen in paintings from the Ming and Qing (1644-1911) dynasties.
Gradually this humble wooden couch became higher and wider and was framed on three sides - but the frames were quite low and there was no canopy. This version came to be known as the luohan chuang, or arhat (Sanskrit for Buddhist disciple, worthy one) bed.
It could also be used for lounging and chatting with friends.
The earliest low beds were said to resemble the seat of a giant smiling Buddha. Luohan chuang was slang for arhat bed. The name caught on and some beds were ornamented with Buddhist carvings.
When opium was introduced by the West in the late Qing Dynasty, some people enjoyed smoking "the big smoke" on their bed. Since the bed was also an important reception area, the opium was offered to friends in the "big smoking bed."