Sleep is important to make sure the energetic body and mind is attained. Sleep must be enough for at least 6 hours for adults and 8 hours for teens and children. Otherwise they will be a bit weak, not active and productive, tired, headache and others. Sleep is like food. Imagine yourself without food. Then, imagine yourself without sleep. Both can bring you to collapse or even death. However, there are certain times you may not sleep. For example, during working hours. You can be fired or being laugh by office mates. Or, you should not sleep on a train or subway because you will miss every single thing around you such as beautiful girls beside your seat. ;-)
P/s; son always sleep...even beside beautiful Korean girls!