Beds used to be much shorter in length for two reasons. People used to sleep in a more reclined position than modern beds, but people on average were smaller. The majority of this difference can be accounted for to some degree by modern diets and healthier environments. But on average, people were shorter than they are today. Some of that is genetic.
Thanks. People became larger, as well, after 1955, when McDonald’s went national. Ummmmmmmm, weighty burgers.