It is often said that the reason we get up so early in the morning is to have the opportunity to be awake - more or less - before the habitual conscious mind can get a firm hold on us. Moving through familiar routines without much mental activity involved, there is the chance for body and mind to experience spaciousness during zazen.
I am often sleepy during afternoon zazen, more specifically during the first half of the period; around the time I hear the six o'clock chimes from up the road, I start feeling more alert. This seems to be the tired body's natural response to stopping after a day of activity, but I have found it a useful place to be - the other day, somewhere close to the tipping point between waking and sleep, I had the sense that I should tilt slightly to the right from the mid-point of the thorassic curve in my spine. Having adjusted my posture, I felt the release of balance and settledness, but since it wasn't dictated by the conscious mind, I have found it difficult to repeat the movement since then, however much I would like to.
Reading Katagiri Roshi this morning, I came to the sentence, "Dogen constantly emphasizes that practice is shikan. Shikan is just wholeheartedness; it is experience, so practice is experience." At that moment, without really thinking about it, I understood this as the energy to go forward and meet things. I also know that recently I have been practising with letting go of some of the forward drive in my everyday attitudes, which I have been doing by noticing a certain bodily tension and allowing the muscles in my ribs to relax. In both cases, it seems that it is allowing the body to function more naturally without so much interference from the mind, like those twilight moments when the brain is not fully in gear.