I recently investigated some reasons why I have been sleep fighting, i.e. kicking and punching in my sleep. Turns out there is a condition called REM behavior disorder (RBD). While I am no expert on sleep disorders, it was still interesting to find that so many people have this condition. There are numerous possibilities as to what the cause is, but since myself and my older brother both exhibit these symptoms it might be reasonable to believe the cause might be genetic. The portion of the brain stem that is supposed to receive the neurotransmitter to cause paralysis is being inhibited somehow. At any rate, when i begin sleep talking, it's normally loud enough for my ears to hear...but most times I don't wake up and it becomes my trigger for lucidity. There was one occasion that remember where I was having two conversations at once, one with a dream character and one with my ex ( it was a while back) it was the weirdest experience, and it should not be possible, but it happened. External audio normally will not wake me up as long as it is not too loud. A person whispering to me while I am sleeping will bleed through into my dream, and sometimes change the dream. So... if you experience sleep walking, talking, or start acting like a sleeping Bruce Lee, then you might find this info entertaining. cheers