answer: #Person2# tells #Person1# that David is full of energy because he takes several short sleep every day, but they don't think David's way fits them.
documents: #Person1#: How come David is always so full of energy?
  #Person2#: He has a strange but highly effective way of sleeping.
  #Person1#: What is that?
  #Person2#: He takes a short sleep for an hour every six hours and has a total of four hours of sleep each day.
  #Person1#: Where did he get that strange idea?
  #Person2#: He read flora a book which said it was the best way for human beings, and he believed it.
  #Person1#: How many hours do you sleep a day?
  #Person2#: I need at least seven hours. I once tried to follow David's example, but it never worked out for me.
  #Person1#: If I sleep during the day, I can never wake up.
  #Person2#: Not everyone is a David I guess.