Of course sleeping is important, but you should not say that it’s the basis of our productivity. I mean, there are people who suffer from anxiety and who cannot sleep well. The thing is that telling people to sleep 8 hours is imposing them a fixed system. Sometimes I private myself from doing things because I didn’t sleep the famous “8 hours”. I personally discovered that no matter how tired you are(trust me), if you really focus you’re attention to what’s going around you will be immersed in reality and thereful, likely to respond successfully.