Pratyahara and samyama - Yogi explains what are these states?

Pratyahara, dharana and dhyana recast as stages of one process: pratyahara begins when the sympathetic and parasympathetic systems balance through heart rate variability, dharana is the no-mind void, and dhyana is integration, where communication with deep brainwaves begins before Samadhi. Includes Maxwell Cade and Anna Wise's warning that meditators can get stuck in silence.