For many teenagers, the hardest part of the school day may begin well before the first bell rings: waking up when their brains are still wired for sleep. 

That biological mismatch is receiving renewed attention in Pennsylvania, where recent updates to the state School Code give districts more flexibility to explore later start times for secondary students. The change does not require districts to move the first bell, but it gives communities a clearer path to consider whether later schedules could better support students’ health, safety, and learning. 

Sleep experts have long argued that middle and high schools should start no earlier than 8:30 a.m., a benchmark supported by major medical organizations. The reason is not simply that teenagers stay up too late. During puberty, circadian rhythms shift, making adolescents naturally sleepy later at night and more likely to need sleep later in the morning. 

“This is not simply a matter of teenagers making better choices at bedtime.” said Indira Gurubhagavatula, MD, MPH, a professor of Sleep Medicine at the Perelman School of Medicine at the University of Pennsylvania.  

The American Academy of Sleep Medicine recommends that teenagers ages 13 to 18 get 8 to 10 hours of sleep each night. However, early school schedules can make that difficult. A teen who does not feel sleepy until 11 p.m. but needs to wake around 6 a.m. for a bus or commute is already falling short before the school day begins. 

Research on later school start times¹ has linked the change with longer sleep duration, less daytime sleepiness, fewer absences, better academic performance, and greater overall well-being, Gurubhagavatula said. “Study after study has shown that when school starts later, teens sleep more, not less,” she said. “When bell times are better aligned with their biology, improvements show up—in how they feel, how they learn, and how safely they move through the day." 

The effects of chronic sleep loss can extend well beyond the classroom. Gurubhagavatula noted that insufficient sleep in teens is associated with more headaches, stomach complaints, daytime sleepiness, visits to the school nurse, depression, anxiety, suicidal thoughts, difficulty controlling impulses, and unhealthy choices around caffeine, nicotine, alcohol, marijuana, food, and exercise. 

There is also a safety dimension. Teens are already among the highest-risk drivers on the road, and sleep deprivation can make it harder to react quickly, process information, and stay alert behind the wheel. 

Sleep also matters for the developing brain, said Raquel Gur, MD, PhD, a professor of Psychiatry, Neurology, and Radiology. During adolescence, the brain undergoes changes that support learning, memory, emotional regulation, and decision-making. Deep sleep helps young people encode, consolidate, and retain what they learn. “Sleep is not something happening off to the side,” Gur said. “It is integrated with the brain’s development during this vulnerable and important period.” 

When adolescents do not get enough sleep, Gur said, the effects can show up in attention, learning, memory, emotional regulation, reward-seeking, and decision-making. “Sometimes people look at a teen’s behavior and say, ‘What were they thinking?’” Gur said. “But in adolescence, the tools for thinking through decisions are still coming online and when sleep is restricted, those tools are even less available.” In practical terms, that can mean a student is not only tired, but also less equipped to manage stress, evaluate choices, and stay focused during the school day. 

One common misconception is that teens could solve the problem by turning off screens and going to bed earlier. Sleep hygiene matters, Gurubhagavatula said, but it does not erase the biological shift that makes teens’ sleep-wake rhythm run later than that of younger children or many adults. 

Another concern is that students will simply stay up later if school starts later. Gurubhagavatula said research has generally shown the opposite: when school schedules move later, students tend to get more total sleep. 

Implementation questions are real. Districts must consider transportation, athletics, after-school jobs, child care, and family schedules. But sleep advocates and clinicians say those challenges should be weighed against the growing evidence that early schedules can affect students’ health and performance. 

Pennsylvania’s school-code language stops short of a statewide mandate, but it acknowledges later start times as an option for districts and provides a structure for communities to study, discuss, and report changes. As many as 50 Pennsylvania districts have already adopted later start times.  

For families heading into a new school year, the debate may seem practical—buses, homework, sports, and morning routines. Yet, science points to something deeper: For adolescents, later start times may better align the school day with a brain and body still under construction. 

Reference:

1) https://www.sciencedirect.com/science/article/abs/pii/S2352721817301547

(Newswise/HG)