If you feel sleepy while practicing, you should change to another kind of work, for example, weeding, washing your face, taking a bath, washing clothes. We should find a way to avoid the obstacle.
Calmness under Unawareness
Calmness under Unawareness is called Piti (rapture), clinging to calmness. This is an obstacle. The cultivating of self-awareness is not to obtain this kind of calmness, but always be aware of the movements.