answer: #Person1# is surprised that Tom slept early and #Person2# explains it's because Tom ran four miles.
documents: #Person1#: Where is Tom?
  #Person2#: He is in the bedroom and fallen asleep.
  #Person1#: What? It's only 9p. m. Now. Why today he went to bed so early?
  #Person2#: He ran four miles and came back dead beat.
  #Person1#: Oh, I see.