Yeah. Have you ever memories that pop up only when you're drunk?
   It's the same idea. When you're at a certain state: body
   temperature, certain state of sleepiness... every dream you ever
   had when your body was in that state previously, whether you
   were 6 yrs old, ,9 yrs old, 20 yrs old, whatever, will be a
   "match" for your body/mind state and will start flooding in. I
   enjoy the flood. It's fun watching them whizz by.