Midnight noise

I awoke the other night to a strange clacking/ grinding noise.  As I slowly woke up I tried to asses where the noise was coming from.  I then realized my jaw was moving and I closed my teeth and locked my jaw.  The noise stopped.  

Stress has caused me to grind my teeth apparently at night.  

I grabbed my iPad, found the next and nearest yoga class at the gym, set my alarm and went back to sleep.  

I have never grinded.... Ground?  Grinded...?  My teeth at night before.   Stress is crazy.