One of the most powerful aspects of drumming and the reason people have done it since the beginning of being human is that it changes people's consciousness. Through rhythmic repetition of ritual sounds, the body, the brain and the nervous system are energized and transformed. When a group of people play a rhythm for an extended period of time, their brain waves become entrained to the rhythm and they have a shared brain wave state. The longer the drumming goes on, the more powerful the entrainment becomes. It's really the oldest holy communion.