I sleep less. I mean, that sounds simple, but I just cut down on sleep. I think having kids grade papers is a great idea, and you could also focus on different assessment strategies that don't involve grading papers. I often have class discussions where I tally grades during the discussion. When the class is finished all I have to do is put the grade in the gradebook.
I tell teachers that there are three aspects of life for our profession- sleep, social/ family life, and career. I chose to be a great mom and a great teacher, therefore, I don't sleep as much as I would like to.