This is something I've seen in another MMORPG called Final Fantasy Online for PS2, PC, and Xbox360. There is a job called Red Mage. They have the ability to cast "Refresh". This gives the person who the spell is casted on more GP per tick weither they are awake or sleeping. The amount per tick could depend on certain faith skills or stats such as int. Let me know what you think or if you have discussed this before.
Refresh
GP cost 25-50
GP gain per tick 3-15
Time before wearing off - 3 mins