I have had this happen .being suddenly woken up by a voice that seems right next to you but is not. but I think i read it can have to do with the wake/sleep cycle and can occur in healthy individuals as well.
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I used to rule the world
Seas would rise when I gave the word
Now in the morning, I sleep alone
Sweep the streets I used to own
I used to roll the dice
Feel the fear in my enemy's eyes
Listen as the crowd would sing
Now the old king is dead! Long live the king!
One minute I held the key
Next the walls were closed on me
And I discovered that my castles stand
Upon pillars of salt and pillars of sand
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