According to the National Sleep Foundation, teenagers on average need 8-10 hours of sleep each night in order to fire on all cylinders the next day. Trouble is, 87 percent of them fall short. Many of them also experience what the medical community calls "phase delay"; they have more trouble falling asleep earlier in the night than in their pre-high school days, possibly due to hormonal changes, which means they want to sleep longer in the morning. There's one big problem: Many schools start classes at roughly 7:30 a.m. If you give a kid one hour to get ready, that's a 6:30 a.m. wake up. GO back 8-10 hours and you arrive at a bedtime of 8:30-10:30. For many teens, that ain't happenin'. Some school districts have opted to move starting times one hour later. The results have been encouraging: lower rates of absenteeism and tardiness, improved academic performance, increased levels of safety (e.g., driving to school), and a diminished incidence of health issu...