Raise and stiffen you arm.
Make a fist. (Help subject achieve this position, then let go)
That’s good. Just like a steel bar, stiff and powerful.
So stiff and rigid and so powerful that the more you try to lower or bend your arm, the stiffer and tighter it becomes.
Try to lower or bend your arm and find it locking stiff; stiff and rigid.
The harder you try, the stiffer it becomes.
When I touch your forehead, your arm drops limply down and you go deeper in sleep. (Tap forehead)