Sleepiness
I went to a Vipassana meditation today, as it happens to be just before my Breema class and in the same neighborhood. There was a lot of drowsiness that came up, and I noticed how awareness sometimes got caught up in it, and sometimes was still aware of its own inherent nature in the midst of it.
Awareness, Identification and Sleepiness
When awareness is mostly or exclusively identified with the small self (and less identified with the absolute, or Big Mind), there is a typical pattern that seems to occur during meditation.
The mind becomes more still, the particles in the muddy water sinks to the bottom and reveal clarity. And if awareness is still mostly identified with the small self, it tends to experience drowsiness and move towards falling asleep.
One reason may be that it experiences boredom. The usual habitual activities of the emotions/thoughts quiet down, and the nature of mind has not yet revealed itself fully. So, there is very little there to keep the interest of awareness.
Another reason is that we are often sleep deprived in our culture. We stay awake through all sorts of distractions and engagements during the day, and when we sit down - the body/mind requires its rest. If awareness is identified mostly with the small self, that too falls asleep.
As awareness awakens to its own inherent nature of formless spacious clarity, it can stay awake even if the small self falls asleep. In the beginning of this process, there is a "thread" of awareness/consciousness throughout the sleep. This is experienced by many people engaged in a spiritual practice, off and on or more continually.