Conversely, there are also a lot of studies that show that when you are tired, your productivity drops quickly, to the point that the total amount of work you can achieve in a 16 hour day just isn't that much. Especially where creativity and lateral thinking is needed - it is best to be rested for that.
Agreed, hence my qualification of "real" work. The gist being really, that you just have to do an hour more real work than your colleagues, and (subject to certain types of work), you may be able to become exponentially more capable.