If you train BJJ (or any kind of submission grappling), then getting put to sleep from a choke is merely a function of life on the mat (like staph infections and cauliflower ear). I remember the last time I was rendered unconscious fondly. I know I had a good dream and I woke up in a nice state of bliss. It's a beautiful thing.
Watch Team HK (Relson Gracie) coach, Todd Tanaka, demo a quality RNC on an innocent white belt student - for educational purposes, of course.* Good stuff.
* please don't try this on your kid sister and/or pet monkey.