It’s often said that we should all be aiming to get eight hours of sleep a night. But could it actually lead you to an early grave? Research shows that sleeping for longer, or shorter, than average is associated with an increased risk of disease and mortality. But what’s causing the health problems, and should you really give up the lie-in? Ruth Alexander looks at the latest sleep science with Dr Gregg Jacobs from UMASS Medical Center, US; Professor Franco Cappuccio from Warwick University, UK; Professor Jim Horne of Loughborough University, UK; and Professor Shawn Youngstedt of Arizona State University, US. *Please note this is a repeat from February 2015* (Photo: Man asleep in a bed. Credit: Corbis)