The Impact of School Start Times on Adolescent Health and Academic Performance

In the early 1990s, a team of researchers led by Brown University’s Mary Carskadon determined that circadian biology drives the delayed sleep-wake patterns of adolescents. ⁽¹⁾ Puberty’s onset marks the beginning of a “phase shift,” with adolescents going to bed later and rising later than younger children. ^{(2, 3, 4)} Typically adolescents are unable to fall asleep at earlier times and sleep in later to get the 9 or more hours ^{(2, 5)} of sleep they need. ^{(3, 6, 7, 8, 9)}

In 1994, physicians began advising school leaders to “eliminat[e] early starting hours for teenagers[.]” ⁽¹⁰⁾ Sleep experts urge a delay in morning classes until 8:30 a.m., or later, for middle ^{(2, 13)} and high school students. ^{(2, 11, 12, 14, 15)} Few administrators have listened, ⁽¹²⁾ instead adhering to school schedules described by preeminent scientists as “abusive,” ⁽¹⁶⁾ “nonsense,” ⁽¹⁷⁾ “deleterious,” ⁽¹⁸⁾ “cruel,” ⁽¹⁹⁾ and “nuts.” ⁽²⁰⁾

Most U.S. high schools schedule classes during the 7 o’clock hour, ^{(2, 12, 21, 22)} while melatonin still pressures adolescents to sleep. ^{(3, 24)} The vast majority of teenagers attending early starting schools meet the morning bell in a sleep-deprived state. ^{(2, 6, 8, 12, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)} “The consequences of this sleep deprivation are severe, impacting adolescents’ physical and mental health, as well as daytime functioning.” ⁽⁴⁰⁾

Students at later starting schools get more sleep, ^{(4, 13, 30, 37, 41, 42, 43)} perform better academically, ^{(13, 24, 37, 44, 45)} have significantly fewer automobile accidents, ^{(31, 46)} report greater motivation ⁽⁴¹⁾ and less depression, ^{(3, 37, 41, 47)} experience fewer physical health difficulties, ^{(37, 41)} are less likely to be tardy or truant, ^{(2, 30, 41, 44, 47, 48)} demonstrate “better performance in attention level, impulsivity, and rate of performance[,]” ⁽¹³⁾ and, according to Brookings Institute economists, will likely earn significantly more money as adults when school begins at “roughly” 9 a.m. ⁽⁴⁹⁾

Policymakers may eventually decide when the school day begins. ^{(50, 51)} Until then, at least during the school year, adolescent sleep sufficiency, a point of concern for the CDC ^{(18, 26, 52, 53, 54)} and the National Institutes of Health, ^{(55, 56, 57)} will substantially be determined by the whims of local school boards. ⁽⁵⁸⁾ To the extent it may be said that there is a “debate” concerning school start times, science favors only one side of the argument. ^{(1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 41, 47, 48, 49, 52, 53, 55, 56, 57)} The other side is governed by unawareness ⁽⁵⁹⁾ and convenience, ^{(60, 61)} busing, athletics, ⁽¹²⁾ and politics, ⁽⁵⁸⁾ rather than education or the needs of children. ^{(62, 63, 64)}

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