Sometimes when I sit before I go to bed and I知 tired, I have the experience that my body suddenly jumps or convulses. It is when my mind begins to wander off into thought fantasy narrative mode and I know that means I知 falling asleep but it isn稚 the jerk upright that happens if I知 falling over. It happens when I知 still sitting upright and it is quite an unnecessarily big thing. Also, isn稚 it a paradox that when my mind is clear, open, aware I can sit for a long time even if I知 tired but as soon as thought narrative creeps in, I fall asleep?
Gassho,
Kenkū
sat & lah