Sleepy Teens in Class: The Case for Later School Start-Times

As my head rested back on the plasticy brown school bus seat, a limp strand of drool hung from my mouth. Over-tired and lulled by the methodical starts and stops of the bus, I had fallen fast asleep on my ride to Wayland High School. Surely this was not a “cool kid” kind of look.

The time was probably 7:00am. With my massive backpack seated beside me and my duffle bag tucked at my feet I couldn’t forget that once the first school bell rang at 7:25am I’d be right back in the cycle of school to sports practice to homework late into the night. Yearning for whatever additional sleep I could get, I tilted my head back onto the sticky upholstery once more.

While my friends and I would often commiserate about how tired we felt during the school day, we didn’t understand the scientific underpinnings of our grogginess beyond our clear preference for sleeping in over waking up early to the blare of an alarm. However, soon after we graduated media erupted with stories about high schools and middle schools nationwide assessing the possibility of pushing back their start-time. Where was such initiative during my days of drooling on the bus, I thought, and what does the evidence for this new concept say?

Though unique patterns of the adolescent biological clock have long been understood, their significance in relation to early school start-times was not brought into the limelight until more recently. Scientists explain that right around the onset of puberty, adolescents experience two major changes in their biological functioning that result in an approximately two-hour “phase shift” of sleep (AAP). One of these changes is a delay in the secretion of melatonin, which is a regulatory hormone released by the pineal gland in the brain. Melatonin keeps our circadian sleep-wake rhythms in check; when the hormone is released we know it is time for bed, and when it “turns off” we start to feel ready for a new day (National Sleep Foundation). Compared to other age groups, adolescents do not experience a sleep-worthy secretion of melatonin until later in the evening, and this secretion subsequently lasts later into the morning. Thus, adolescents don’t typically feel tired until about 11:00pm, and they crave a hearty sleep-in.


This phase shift is further complemented by the second widely proven aspect of adolescents’ sleep tendencies: an altered “sleep drive” (AAP). Before puberty children experience a fast accumulation of pressure to fall asleep. After puberty, however, adolescents take longer to feel sleepy in response to sleep loss (AAP).

Indeed, the biological shifts of adolescents’ sleep would indicate that teenagers are far from suited to be waking up early in the morning for school. According to the US Department of Education’s 2011-2012 statistics, about 43% of the approximately 18,000 public high schools in the US have start-times before 8:00am. When middle schools – which usually have slightly later start-times than high schools – are pulled into the picture, we see the national average start-time increase to 8:03am. Interestingly, Alaska reports the latest average middle school/high school start-time of 8:33am, and Louisiana reports the earliest average start-time of these schools at 7:40am (CDC).

Meanwhile, it is recommended that adolescents try to sleep for 8.5 – 9.5 hours per night (AAP). Therefore, if we factor in the amount of time it takes for weary teenagers to be “dragged” out of bed in the morning, get ready for school, and make their way to school, students need to wake up sometime between 6:00am and 7:00am. In turn, that means their bedtime should ideally be between 9:00pm and 10:00pm.

Not only does the early rise time enforced by school schedules clash with the biological clocks of adolescents, the corresponding ideal bedtime is also unrealistic given teen’s natural onset of sleepiness and the jam-packed lives that they typically lead. A large collaborative study on high school start-times done at the University of Minnesota points out that teens in the US are often engaged in many after-school extracurriculars, learning how to drive, and possibly working a job. Combined with school and schoolwork, these activities result in days that are stretched thin with nary an early bedtime in sight.

While the effects of not getting enough sleep are detrimental at any age, consequences are especially great for adolescents because of the amount of change that their bodies and minds are already undergoing. Indeed, minimized snoozing leaves little time for essential brain maturation processes like intensified synaptic connectivity, refinement of executive function systems, and gray matter pruning (Giedd, 2009). When the normative trajectories of these adolescent neurological processes are hindered, functions like decision-making, activation-reward, memory consolidation, and learning are hindered as well (Giedd, 2009). Based on survey results, the University of Minnesota researchers note that an accumulation of inadequate sleep (as in less than the recommended minimum of 8.5 hours), can result in higher risk for obesity, the development of mental health and behavioral problems, and high risk behaviors like substance abuse.


Other studies that have surveyed student populations before and after school start-time changes have found overall reductions in absenteeism, tardiness, and teen car crashes (AAP). One study of middle school students in Wake County, NC found that when the start of school was delayed by one hour, to approximately 8:30am, students in public schools achieved an average of two percentile points higher on math tests, and one percentile point higher on reading tests (Edwards, 2012). Moreover, researchers found that when adolescents’ school start-time was pushed back they were more satisfied with their sleep, made fewer trips to their schools’ health center, and were more likely to eat breakfast (AAP). While researchers acknowledge that their findings are correlational and not necessarily revealing of a direct causal relationship, there is no denying that if adolescents are able to get a healthier amount of sleep, they’ll be more happy, healthy, and productive.  

So: why aren’t schools latching onto the opportunity to improve the mental wellbeing – and likely the more tangible attention, productivity, and success – of their students? Afterall, as Brown University researcher Mary A. Carskadon has poignantly said, “Given that the primary focus of education is to maximize human potential, then a new task before us is to ensure that the conditions in which learning takes place address the very biology of our learners” (Carskadon et al., 1999).

Well, as with most things, the task of changing school schedules is far easier said than done. Busing schedules would need to change, sports practice and games would need to be adjusted, and teachers, parents and siblings would have to replan their lives. Along these same lines, entire school districts are better off changing in unison so as to keep transportation and extracurriculars on the same schedule, but such an upheaval is understandably more complicated than changing the routine of a single school.


A quick search on the Wayland Public Schools homepage has led me to believe that students are most definitely still falling fast asleep on the bus just as I did not too long ago. Though there is a section entirely dedicated to “School Start Time” research and nationwide campaigns on the website, the Wayland middle school still begins mightily at 7:35am and the high school starts at 7:30am.

Hopefully, at the very least, educators, parents and students at Wayland – and at schools worldwide – have learned something from the uptick in adolescent sleep research and recent growing conversations about school start times. There really is no time like the present to be fostering student growth and wellbeing! If school clocks aligned with adolescent biological clocks, it sure seems like teens would be excelling at higher rates instead of falling asleep in first period History class.



Adolescent Sleep Working Group; Committee on Adolescence; Council on School Health. (2014). School start times for adolescents. Pediatrics, 134, 642–649.

Backgrounder: Later School Start Times. (n.d.) National Sleep Foundation. Retrieved from

Edwards, Finley. (2012). Do Schools Begin Too Early? Education Next, 12(3). Retrieved from

Giedd, J.N. (2009) Linking adolescent sleep, brain maturation, and behavior. Journal of Adolescent Health, 45(4): 319–320.

Wahlstrom, K., Dretzke, B., Gordon, M., Peterson, K., Edwards, K., & Gdula, J. (2014). Examining the Impact of Later School Start Times on the Health and Academic Performance of High School Students: A Multi-Site Study. Center for Applied Research and Educational Improvement. St Paul, MN: University of Minnesota.

Wheaton, A.G., Ferro, G.A., & Croft, J.B. School Start Times for Middle School and High School Students — United States, 2011–12 School Year. Centers for Disease Control and Prevention: Morbidity and Mortality Weekly Report. Retrieved from


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