Zen is about hypnogogic states, and these states are a part of everyday life that nobody recognizes. A stream of thought, a concentrated effort, falling asleep: hypnogogia reigns. The question is how these states are entered as a matter of course, and my answer is that they are entered out of necessity in the movement of breath, as the sense of place and the ability to feel respond.
In the cross-legged posture we put ourselves in a position where the sense of location and the ability to feel must respond to the necessity of breath (sooner or later). In fact, the sense of location and the ability to feel engendered through the necessity of breath can get up and walk around. Once that happens, who will sit back down to zazen? Who will walk out the door at the end of the retreat? And if the necessity is falling asleep, why would anyone drink a red bull to deepen an ease of posture in the cross-legged position when their necessity is otherwise, or pursue anything other than where they are right now and what they feel in the movement of breath?
“Good morning, where am I”- Sasaki at Cobb mountain last spring.