There is over 25 years of research and ample evidence demonstrating that starting school later in the day for high schoolers (and even middle schoolers) has the potential to substantially improve school performance (Hamilton Project, 2011), yet most high schools are still starting first period before 8:00 a.m. Although most people have some familiarity with the medical research that outlines a shift in adolescents’ sleep/wake cycle, and the educational research that demonstrates the benefits of a later start time, this research brief is intended to define the full extent of the problem and provide a thorough review of the negative impact of sleep deprivation on the developing minds and bodies of adolescents. Shifting to a later high school start time is complex because of many interrelated factors such as transportation, family schedules, childcare and athletics, however an effective change process begins with an in-depth understanding of the identified problem, local data regarding the impact of the problem, and research and best practice regarding how other districts have successfully navigated such a change in policy.
During adolescence, bedtime shifts to later in the evening as a result of biological maturation and an increase in academic workload, athletics and social activities. Despite a later bedtime, adolescents often must wake up even earlier than they did during childhood due to early school start times, which very often results in sleep deprivation (Hasler & Clark, 2013). Different amounts of sleep are needed, on average, during different stages of life, with younger people requiring more sleep than adults. The usual recommendation for preschool children is 11 to 12 hours, school-age children 10 hours and teenagers 8.5 to 9.5 hours per night (Carroll, 2016). According to the National Sleep Foundation, only 14% of adolescents get the recommended number of hours of sleep per night. Approximately 70% of adolescents get less than eight hours of sleep on a typical weeknight (Boergers, 2015). This is a very concerning statistic given the wide range of negative consequences of sleep deprivation, especially during adolescence.
The Science of Circadian Rhythms.
Human sleep and wake phases are matched to the dark and light periods of each day. Sleep-wake timing is influenced primarily by circadian rhythms, but is also impacted by scheduling influences including the start of the school day (Hasler & Clark, 2013). Research highlights the relative importance of circadian rhythms (this is the most influential aspect of sleep) to adolescent functioning (Short, Gradisar, Lack & Wright, 2013). During this stage of development, adolescents appear to become resistant to the homeostatic sleep drive that accumulates with time spent awake (Hasler & Clark, 2013). It’s clearly a matter of biology, not choice, that teenagers are unable to fall asleep before about 10:45 p.m. and that their brains remain in sleep mode until about 8 a.m. This delay in circadian rhythms is directly related to hormonal changes during puberty (Wahlstrom, 2017).
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