Sleep is so important to our good health. Sadly, many Americans, including children, have a chronic deficit of sleep. We have all had (or been) students who yawn frequently, who are excessively crabby, and who may fall asleep in class. Sleep debt has negative effects on brain function, cognitive abilities, energy levels, and emotional balance. The effects of not getting enough sleep are cumulative and can lead to problems, like interfering with coordination, balance, memory, focus, and decision-making, as well as contributing to obesity.
Growth hormones are released during sleep. Cell and tissue repair and muscle mass development take place because of that. You can see how chronic sleep shortage would impact a child's normal physical development.
I'm borrowing this sleep chart from Wilson Elementary in Kenosha, Wisconsin. It will be a good is visual to pass along to parents. The demands of school are challenge enough without hampering children's efforts because of lack of sleep.