It does not have to be that way.  Is just an idea.  However u want to do it is fine.

  I just meant that the more scared you get inside your dream the more likely it would be for the dream to come to life.  The gene Is activated by fear and the more scared they are in the dream the easier it would be for the gene to activate and thus the nightmare become reality through it.   If that makes sense.  As I said though I am just making this shit up as I go so is all changeable and flexible.  If you have another idea on how it would work then that is cool too.  


Was kinda thinking that the gene is not really active except in the dream state.  However the people that can control their nightmares might be able to get around that somehow so that they could activate it at will and bring nightmares I to reality but it would maybe drain them badly or something.  Like a check and balance thing so they don't get too overpowered and such.  Idk.