Anthropologists have discovered we didn't used to sleep for eight hours straight and we shouldn't either.
See also: Top tips for a good night's sleep as you get older
See also: How to loose weight when you sleep
The post-lunch dip, when we lack energy and just want to sleep, is a biological phenomenon. Our body clocks simply aren't wired to work throughout the day without taking a break.
But try explaining that to your boss..