for - dream theory - dreaming as default state of brain

• Dreaming can be seen as the "default" position for the activated brain
• when it is not forced to focus on
  • physical and
  • social reality by
    • (1) external stimuli and
    • (2) the self system that reminds us of
      • who we are,
      • where we are, and
      • what the tasks are
    • that face us.

Question - I wonder what evolutionary advantage dreaming would bestow to the first dreaming organisms? - why would a brain evolve to have a default behaviour with no outside connection? - Survival is dependent on processing outside information. There seems to be a contradiction here - I wonder what opinion Michael Levin would have on this theory?