At Quartz, Akshat Rathi challenges the claim that modern times has caused a sleep epidemic.

According to a survey conducted by the US Centers for Disease Control (CDC) between 2005 and 2007, more than 30% of adults slept less than six hours a night. The National Sleep Foundation’s own surveys reveal something similar: more than 20% of people in 2009 were sleeping less than six hours compared to only 12% in 1998. The CDC declared that insufficient sleep was becoming a public health epidemic….

However, a 2010 analysis, published in the journal Sleep, which used data from a different set of surveys conducted between 1975 and 2006, found very different results. It showed that the proportion of short-sleepers (those sleeping less than six hours) hadn’t changed much in the last 30 years. And, more surprising still, that proportion was only 9.3% in 2006.

Likewise, the studies from other countries suggest that there’s less of a sleep epidemic problem than we thought.

A 2012 systematic review of 12 studies from 15 countries, published in Sleep Medicine Reviews, showed that, between 1960 and 2000, total sleep times across these countries hasn’t changed much at all. They increased by less than an hour per night in seven countries (Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands), decreased by less than 30 minutes per night in (Japan, Russia, Finland, Germany, Belgium and Austria), and showed no change in Sweden and the US.

But even if the data about chronic sleep deprivation are harder to make sense of than we think, the science around the consequences of sleep deprivation on cognition, performance, decision-making, and so on are still very compelling. It may not be the case that surgery and ER residents are working more hours than their predecessors fifty years ago (though I would argue that they’re less likely to be able to come home and sack out on the couch and assume that their wives will take care of everything), but we have a clearer understanding of how the odds of making a critical mistake compare at hour 6 of a 48-hour shift, and hour 46.