“Children of parents who reported having a rule about bedtime scored about 6 percentage points higher on an assessment of their vocabulary compared with children whose parents did not report a rule about bedtime. They scored 7 percent higher on assessments of early math skills. The differences between the children with rules and those whose bedtime customs were less rigid were significant enough to merit attention. Studies done on teenagers and college students have further confirmed the benefits of regular, restful sleep on performance and test scores.”
–David B. Agus. The End of Illness. New York: Free Press, 2011. Quote on page 252.