If I close my eyes and focus on the backs of my eyelids while holding my breath, when my lungs scream for air and I am just about to pass out, my consciousness explodes and the darkness behind my eyes expands and I enter like a rocket ship deeper into the meditation but then I must gasp for air and my consciousness resurfaces to my senses.
(It’s as if you can organically micro-dose “fear of death” and it brings you immediately deeper into the meditation).