When a team is spread out on multiple enemies multiple people will be taking damage due to resulting agro issues. in this case us healers go through mp fast as we are focusing on whole party not just the tank. You often don't need to sleep if dps backs the tank effectively. Sleep I find to be most effective in such instances but again its due to shotty dpsing and usually letting the part know is important cause they'll just wake your sleeps for the same reason you need to use it in the 1st place. I as healer find throwing u a mark on the enemy tank is attacking just as effective sometimes.