Originally Posted by
Heathrow Harry
there is no simple test for fatigue/tiredness compared to that for drinking.
Mythbusters dedicated an episode to the "Deadliest Catch" TV show where crab fisherman in the Bering Sea work for days without sleep. In that particular scenario, they measured weather or not a 20-minute nap would improve performance in fatigued persons. If I recall correctly, it did.
They did tests while fully rested, while totally fatigued without any sleep, and while fatigued, but with 20 minute naps.