answer: #Person2# tells #Person1# that #Person2# feels weak because of jet lag.
documents: #Person1#: How do you feel?
  #Person2#: I'm getting sleepy.
  #Person1#: You've had so long a flight.
  #Person2#: Time difference also makes me feel weak.
  #Person1#: Oh, I forgot about it.
  #Person2#: It's four o'clock in the morning in Chicago now, but it's time to go to bed in Shanghai.
  #Person1#: Don't think so much. Take a good sleep and you'll feel better soon.