This question is a follow-up to yesterday's post, in which I recommended at least seven hours of sleep. How much do Americans sleep today in comparison to a hundred years ago?
As Matthew Walker mentions in Why We Sleep, 98% of the population of the United States sleep six hours or more a night a hundred years ago. Today, less than 70% do, according to a 2013 National Sleep Foundation survey highlighting this sleep deficiency.
More than 65 percent of the US adult population fail to obtain the recommended seven to nine hours of sleep each night during the week. […] [C]ountries where sleep time has declined most dramatically over the past century, such as the US, the UK, Japan, and South Korea, and several in western Europe, are suffering the greatest increase in rates of physical diseases and mental disorders.