We tend to attribute their success to corruption, exploitation, or brute-force (given their population). But, could it be that they have something going for them? Maybe they are as capable as we are, as productive as we are, and also are putting the extra work.
Don't get me wrong, I believe this is totally unhealthy for individuals. But it doesn't seem unreasonable for me that a highly capable and motivated individual would indeed produce more in 16 than in 8 hours, health and normal life aside.