Some people can get away with that, others can't.

Sleep is really weird when you think about it, and Edison was clearly wrong. Pretty nearly everything sleeps. Most animals live in constant fear of becoming dinner, yet we shut ourselves down for hours at a time during which we are totally vulnerable. If it was possible to evolve a different strategy, SOME animal would have done so, because the cost is clearly so high. The fact that all vertebrates sleep must mean that sleep is essential, even if we don't really know why. Whatever role it fills, it is right up there with breathing and eating (a bit below breathing, and a bit above eating).