In the old days, people had to make the ropes tight before they went to bed. Do you know the reason why they had to make the ropes tight? Is that because of the shape of the bed in the old days?
It was all about how they were constructed. There were no box springs or other such devices under the mattresses.
http://historyiselementary.blogspot.com/2010/10/ti-ti-tightening-those-ropes.html