Recent evidence on worldwide trends on sleep duration

It is often claimed that we are living through a global sleep loss epidemic where, as a society, we increasingly get less and less sleep. However, our previously published systematic review of all relevant studies until May 2011 failed to find strong evidence that this had happened worldwide. In this current review, we updated that search and found 5 new articles with data from 12 countries starting in the 1960s–1980s and culminating in 2001–2012. We still find little evidence for the claimed epidemic as different countries have increasing, decreasing or stable sleep. There remain strong concerns about methodological quality in many of the studies and the effect of the rise of smart phones and tablets cannot yet be assessed. We also found data in 5 reports about 4 countries where markers of sleep quality do seem to have declined.