A common-sense reason to start school later in the day:
The biology of human sleep timing, like that of other mammals, changes as we age. This has been shown in many studies. As puberty begins, bedtimes and waking times get later. This trend continues until 19.5 years in women and 21 in men. Then it reverses. At 55 we wake at about the time we woke prior to puberty. On average this is two hours earlier than adolescents. This means that for a teenager, a 7 a.m. alarm call is the equivalent of a 5 a.m. start for people in their 50s.
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Mary Carskadon at Brown University, who is a pioneer in the area of adolescent sleep, has shown that teenagers need about nine hours a night to maintain full alertness and academic performance. My own recent observations at a U.K. school in Liverpool suggested many were getting just five hours on a school night. Unsurprisingly, teachers reported students dozing in class.
Evidence that sleep is important is overwhelming. Elegant research has demonstrated its critical role in memory consolidation and our ability to generate innovative solutions to complex problems. Sleep disruption increases the level of the stress hormone cortisol. Impulsive behaviors, lack of empathy, sense of humor, and mood are similarly affected.
This rings true based on my own observations -- the empirical evidence, if you will -- and my own memories of high school. I can tell you a lot about when I had certain classes. English in my junior year was the period right before lunch, for example, and world history in my sophomore year was the next-to-last period of the day, right before algebra. But what I had in first period is a blur for three out of four years. I only remember it was general science in my freshman year because the teacher threw an eraser at me for dozing through his lecture. Can I sue him retroactively for creating a hostile learning enviornoment and messing with my delicate self-esteem?
"Evidence that sleep is important is overwhelming." Well, duh.