“Kids as young as age 9” may engage in misconduct and other risky behaviors after school. Experts say insufficient sleep contributes to student misbehavior. Understand why. (Read Part II here.)
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Starting middle and high schools at a developmentally appropriate time, 8:30 a.m. or later, increases adolescent sleep, improves academic performance, and fosters student mental and physical health, decades of studies show.
Later school start times also have a largely unheralded benefit: Classes typically end later in the day. Reducing after-school hours without adult supervision potentially diminishes opportunities for youth misconduct.
In reporting on these topics, we as education reporters need to explain the science of adolescent sleep needs and sleep timing, the benefits of starting school at 8:30 a.m. or later, and the adverse consequences of earlier start times.
In Part I of this two-part series for the Education Writers Association, I review benefits of sufficient sleep for adolescent school performance and well-being, the contribution of insufficient sleep to adolescent delinquency and the harmful impact of long commutes on student sleep time.
In Part II, I discuss challenges facing after-school program providers along with those facing communities considering adopting developmentally appropriate school start times. I also report burgeoning efforts to mandate healthy school start times via legislation. Reporting tips and suggested reading are also included in the second part.
Let’s get started with Part I, which includes important background and context to use in your reporting:
Middle school students need at least nine hours of sleep, and high school students need at least eight hours of sleep on school nights for optimal alertness and well-being, according to the Centers for Disease Control and Prevention (CDC).
That finding stems from studies launched in the 1970s by Mary Carskadon, a professor of psychiatry and human behavior at Brown University. She directs the Center for Sleep and Circadian Rhythms in Child and Adolescent Mental Health at the E.P. Bradley Hospital in Providence, Rhode Island.
Changes in the brain at puberty, Carskadon found, make it hard for most adolescents to fall asleep before 11 p.m. or later and push them to stay asleep until 8 a.m. or later if undisturbed. Early school start times, which are out of sync with these biological imperatives, limit the amount of sleep most adolescents can get. Going to bed earlier does not help adolescents fall asleep earlier. Sleep occurs only when the brain and body are ready to sleep.
Researchers worldwide have replicated Carskadon’s findings. The scientific evidence from these studies prompted the American Academy of Pediatrics (AAP) to issue a landmark statement in 2014 recommending that the nation’s middle and high schools start at a developmentally appropriate time, 8:30 a.m. or later. The National Parent Teacher Association, and dozens of other health and education groups have endorsed this recommendation.
In May 2025, President Trump’s Make America Healthy Again Commission released a report, “Make Our Children Healthy Again,” that called adolescent sleep deprivation “a nationwide sleep crisis.” The report cited screen use and academic pressure as contributors to this problem. In a June 2025 letter to U.S. Health Secretary Robert F. Kennedy, Jr., the American Academy of Sleep Medicine emphasized the pervasive impact of early school start times on chronic sleep loss in adolescence.
“The AASM recommends that middle school and high school start times should be 8:30 a.m. or later,” it said, “to support an adequate opportunity for adolescents to obtain sufficient sleep on school nights.” The AASM also urged the commission to support a federal study to examine the relationship between school start times and adolescent health, well-being and performance.
U.S. public high schools start at 8 a.m. on average, the National Center for Education Statistics reported in 2020. Only 40% of the schools started classes between 8 a.m. and 8:29 a.m. In Louisiana, the state with the earliest start times, high schools opened at 7:30 a.m. on average. School buses begin picking up students 5 a.m. to 6 a.m. in some communities across the nation.
Nearly four out of five U.S. high school students sleep less than the recommended minimum of eight hours on school nights, the CDC reports. Girls, 12th graders, and Black students top its list of students obtaining the least sleep.
The CDC and AAP cite numerous adverse consequences adolescents who average less than eight hours of sleep per night commonly experience.
These teens are more likely to engage in crime, and they’re more likely to:
In June 2022, Baltimore City Public School (BCPS) officials announced plans to start its 40 high schools in the 2022-2023 school year 30 minutes earlier on average than in the previous year, most at 8 a.m. or earlier and some as early as 7:30 a.m. While BCPS cited the national school bus driver shortage as the reason for the change, only 2.6% of its middle and high school students use school buses. BCPS provides buses only for students with Individualized Education Plans or IEPs. Most of its 22,000 high school students use public transportation, often involving transfers, to get to school. That requires most to start their day between 5 a.m. and 6 a.m.
Sleep and public health experts voiced their concerns about the 7:30 a.m. start time to BCPS, to no avail. The experts responded by producing a report, “Later School Start Times for Adolescents in Baltimore City Public Schools: Opportunities and Recommendations.” The report, published in September 2024, was funded by the Baltimore-based Abell Foundation, which is committed to improving health, economic, and educational outcomes for locals.
Insufficient sleep and poor-quality sleep contribute to delinquency, according to Dylan Jackson, a co-author of the report and an associate professor of population, family, and reproductive health at the Johns Hopkins Bloomberg School of Public Health. Jackson and other contributors to the report described their findings in a panel discussion at a national conference of the nonprofit parent-led advocacy group Start School Later in Baltimore last October.
Delinquency in many children reflects unmet health needs, such as a safe home and adequate food, Jackson said. “We see kids as young as age 9 engage in early onset delinquency,” he reported, “when they are sleep-deprived.”
Younger teens most often engage in crimes, such as shoplifting or painting graffiti with friends, he noted, while older teens may act on their own to rob a store, for example.
Delaying school start times can help prevent such behavior, he said, both because well-rested kids are less likely to be disruptive and the school day ends later. “Unstructured time creates opportunities for pushing boundaries,” he said, “and, in some cases, for criminal activity.”
Violent crimes by youth aged 7-17 years peak between 3 p.m. and 7 p.m. on school days, the hours when the least amount of adult supervision is available in the community, Sam Abed, director of the Washington D.C. Department of Youth Rehabilitation Services, said at the same panel session. Violent crimes include murder, sexual and other types of assault, robbery, and kidnapping.
In his previous position as secretary of the Maryland Department of Juvenile Services, Abed said, legislators asked him, “What can you do to prevent juvenile crime?” His response: “Start school later!”
Children in Baltimore City and other low-income urban environments face many impediments to sleep, including neighborhood noise and bright street lights, Laura Sterni, an associate professor of pediatrics at the Johns Hopkins University School of Medicine, director of its pediatric sleep center, and an editor of the Abell report, said at the conference and in a follow-up interview for this report.
A parent’s work schedule may mean dinner times vary from day to day, she said. Children living in low-income homes may share a bed with siblings or sleep in a room in which other family members talk or watch television in the evening. Some may sleep at the homes of relatives or friends on different nights while a parent works. Some report experiences that interfere with their sleep, such as hearing or witnessing gunshots. Children often express fears about police activity in their neighborhood or lack of it.
“Anything we can be doing as a society to help children get the sleep they need,” she asserted, “we should be doing.”
Some people worry that when school starts later, kids will stay up later. “They don’t,” Sterni said. “They sleep when they have the opportunity to sleep, and the time fits their biological schedules.”
Journalists can provide a public service by raising awareness of the well-documented effects of inadequate sleep, she asserted, and by reporting the benefits of starting school later.
Last February, The Baltimore Banner published findings from its study of Baltimore City students’ commutes on public transit. Data reporter Greg Morton and education reporter Liz Bowie mapped every city middle and high school student’s commute and tracked the location of every Maryland Transit Administration bus for months, more than 4,000 unique trips.
In their analysis, the first of its kind, they said, they found that it’s nearly impossible for BCPS students using public transit to arrive at school on time every day. Nearly two-thirds of BCPS students use public transit to get to school. When the transit system runs on time, Morton and Bowie found, a typical city student’s commute to school takes about 40 minutes, more than twice as long as the average school bus commute in the Baltimore County Public School System and longer than the average Baltimore City adult’s commute to work. Some students’ trips take more than 90 minutes each way.
Some 60% of the students need to transfer at least once on their way to school. If they miss a connection, their commute may last 20-30 minutes longer. Students’ commutes also are stressful. “They stand in drenching rain, endure sexual harassment from strangers and witness violent fights on buses,” Morton and Bowie reported. One teen reported witnessing a stabbing.
In their attempt to get to school on time, some students set their alarm clocks for 5 a.m. About 81% of BCPS high school students report sleeping less than eight hours on school nights, Amy Wolfson, a professor of psychology at Loyola University Maryland in Baltimore, and a co-author of the Abell report, said in an interview for this report.
Because most BCPS students have long commutes, starting classes at 8 a.m. or even 8:30 a.m. still would favor the small number of students whose parents can drive them to school, she added. A 9 a.m. start time would offer all BCPS students a greater opportunity to obtain adequate sleep, said Wolfson, who is also an adjunct professor of mental health at the Johns Hopkins Bloomberg School of Public Health.
BCPS early start times undermine student health and learning, Wolfson said, adding, “The school system has been non-responsive.”
BCPS recently posted its 2025-2026 bell time schedule, with 7:30 a.m. start times still in place. The BCPS communications office did not respond to my queries about school start times for this report or provide a spokesperson to address relevant issues.
Learn more in Part II of this series.
Lynne Lamberg is a freelance science writer/editor who focuses on sleep, adolescents, school start times, and mental health. She is a contributor to Psychiatric News and the book editor of the National Association of Science Writers. She also is a member of the advisory board of Start School Later. Follow her on BlueSky @lynnelamberg.bsky.social and X @LynneLamberg.
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