Why do I get sudden urges to move or stretch when I'm finally calm?

Right as I come to the state of profound silence, I experience a sudden overwhelming physical desire to stretch myself or move my shoulders. This desire distracts my concentration each and every time and is so frustrating. I would like to know whether this is some physical discharge of unspent energy that does not permit to be perfectly calm or whether the thing is that I have to stretch some more before I sit. (Varun, 19/12/1997, 1 AM)