Throughout childhood, kids spend about 40 percent of their time asleep. As large as that number seems, its all part of necessity: sleep is an important part of a childs physical and mental development. Sleep deprivation can lead to behavior problems, learning difficulties, and, surprisingly, obesity. Good sleep and solid PE programs are gateways to great childhood health. Unfortunately, children are notoriously difficult to put to bed, so here are a few tips to help your kids develop good sleep habits.