Back to school: Later start times. Well-rested kids Zzzs to A's. - latimes.com

With classes that start as early as 7 a.m. and buses that pull up long before sunrise, some 80% of American kids in grades 6 through 12 are falling short of sleep recommendations during the school year, according to research by the National Sleep Foundation, a sleep advocacy group.

Overtired kids, studies suggest, struggle with depression. They gain weight and get in more car accidents. Their grades suffer. And many turn to caffeine, with questionable results for productivity and unknown effects on the development of young brains.