Activity all across the braindecreases dramatically. If you wake people up out of this...

[narrator] Activity all across the brain
decreases dramatically. If you wake people up out of this state
and ask them what they were thinking, they'll say,
"Nothing, let me go back to sleep." [narrator] But then,
an hour and a half later, something odd happens. The brain roars back to life. [Poe] Our brain waves
look exactly like we're awake