The only ways I know are the paralyzed and unconscious conditions, as well as the assassination capacity of the murderer thief.
The only ways I know to impose the paralyzed condition are the spells hold the person and hold monster; and the unconscious state through the spells to sleep, eyebite L7 (can cause sleep), and symbol L6 (can cause sleep).
And maybe the order Spell to cause sleep for 1 round if the DM allows it.
So, to do this fairly reliably and not be above level 10, go back to to sleep, and hold the person/hold monster.
Are there other ways?