Analysts from Podio, developing software for project management and tools for remote commands, made infographic. It explains when and why mankind has decided to work for 8 hours per day and the reasons why this system is not relevant anymore. Their results are built on a whole arsenal of different studies and articles, the full list can be found here.
Experts believe that in the modern world it is more logical to focus on the quality of performance rather than its duration. People who work less, but focused, achieve more significant results than those who work longer, but in prostration.
Original material here.