In describing my research position to other classmates, the first reaction has been that shifting school hours would have no effect on sleep quality and quantity of students; they would accordingly shift their own hours, resulting in no net gain of sleep, while acting as an inconvenience to the rest of society.  My first assertion is that adapting school hours to intrinsic adolescent sleeping patterns would increase the amount of sleep students gain.  The hours at which students fall asleep is dependent upon an internal biological clock that is difficult to change.  By shifting school hours to suit this clock, students would maintain a similar bedtime while increasing the amount of sleep.  

Sleep time is dependent upon environmental factors, on sleep/wake homeostasis, and the circadian system.  Sleep/wake homeostasis describes the balance between how long a person has been awake with how long and how deeply one needs to sleep.  This would partially account for adolescent sleep patterns over the course of the week, where students sleep more on the weekends to account for lack of sleep during the week.  

The circadian sleep pattern, however, describes the sleep shift in adolescents over the course of the day.  Sleepiness is initiated in part by the secretion of melatonin, a hormone.  Studies have shown that melatonin secretion in adolescents is shifted to a later hour than that in adults and children.  Melatonin secretion is dependent upon light exposure, and researchers suggest that adolescents are more sensitive to light, even at night, pushing back the hours of melatonin secretion and resulting in a later bedtime and less deep sleep.  Melatonin has also been shown to be related to pubescence, which would explain why sleeping patterns tend to shift at a similar age.  Sleep/wake homeostasis patterns may also undergo rearrangement during adolescence.  

Schools that changed their starting times have supported the idea that intrinsic clocks play a significant role in determining sleep times.  Even after changing school hours, students in these schools reported a bedtime consistent with that before the change.  

The sides

Those who argue that schools should start later in the day must agree that adolescents need more sleep and that this would be provided by a later school starting time.  

There are few arguments against the necessity of sleep.  While the function of sleep is still a subject of scientific study, sleep is shown to be necessary for mental and physical well-being. In adolescents, sleep deprivation has been tied to increased probability of accidents and injury, while continued lack of sleep into adulthood is tied to such diseases as diabetes, obesity, and heart disease.  Sleeplessness also increases irritability and causes depression and fatigue (although some note that other factors are responsible for adolescent irritability as well). Adolescents should sleep at least nine hours a night.  The average is closer to seven, not accounting for the fact that many sleep less on school nights and try to compensate on weekends.  

Whether a later starting time would provide extra sleep is less conclusive.  Adolescent sleep cycles are shifted by biological and behavioral factors, and a later start time would be better suited to these cycles.  Studies have shown that adolescents perform better later in the day and that for many, falling asleep earlier is biologically impossible.  Schools with later start times have reported that students take advantage of this time to sleep, rather than staying up later; this further supports scientific evidence that sleeping patterns are biological and not a matter of choice.  Studies of these schools support arguments that a later start time improves academic performance and student health.  

Arguments against later start times focus upon the inconvenience.  Students involved with athletics, work, extracurriculars, and other activities have difficulty scheduling these in after school and coordinating transportation, particularly when the rest of society functions on a different schedule.  Others argue that adolescent sleeplessness is caused by factors of the lifestyle- such as caffeine intake, use of computers and television, and busy schedules- that would be unaffected by changing school hours.  

Overview

Adolescence has been stereotyped as a period of lethargy, of laziness, and even of anti-intellectualism.  But perhaps those that make these judgments are working with adolescents at the wrong time of day.  

Research confirms that adolescent circadian sleep cycles differ from those of adults.  Where an adult may be wide awake at 7 AM, adolescents generally are not alert until 10 AM.  By this time, most schools have been in session for a couple hours.  Students take their first few classes, even standardized exams, before their internal clocks allow them to function at their best.  

Schools should adjust their start times to adapt to these shifted sleep cycles.  This shift would not encourage laziness or antisocial sleeping patterns, but is a necessary step toward improving student performance and health.  

For my classmates, sleep deprivation is not only common, but taken for granted.  The nine hours of sleep preached by health experts is a laugh for students who are occupied with homework, athletics, work, extracurriculars, and other activities.  But I have wondered why students struggle to stay awake in class because they are up late at night to do homework.  How does a student escape this vicious cycle with GPA's intact?  The later starting time is a plausible answer, supported by experiment and biological studies.