*One of the most acclaimed sleep researchers, Daniel Kripke, said there's never been any evidence to back the 8-hour rule. In his most recent study, Kripke found that "people who sleep between 6.5 hours and 7.5 hours a night, live the longest, are happier, and most productive."
*What's even more interesting here is that sleeping longer than that might actually be worse for your health.
source : http://lifehacker.com/5933568/how-much-sleep-do-you-really-need-to-work-productively
