I’ve only seen one person pass out in class before and it was early on in half moon as well. And it’s a pose where I’ve gotten a little light headed once or twice myself.
My suspicion is that it’s due to the tendency to hold your breath in this position. I know I’ve caught myself holding my breath, as it seems “easier” to go farther into the pose when you are not inhaling. While it’s good for max flexibility, not so good for staying conscious!
If you’re really focused on maintaining consistent deep breaths then maybe it’s something else, but that seems like the most obvious possibility.
