The hidden cost of early morning classes on teen student brains

The first alarm can feel like a small act of cruelty. It goes off while your brain is still deep in night mode, and the school day demands you switch on anyway.

For many teenagers, that mismatch is not a character flaw or a failure of “time management.” It is biology. During adolescence, the body’s internal clock shifts later, making it harder to fall asleep early, even when you know you should. Early school start times lock in early wake-ups, and sleep debt piles up through the week.

“This is concerning, as chronic sleep deprivation not only affects well-being, but also has a measurable impact on mental health, physical development and the ability to learn,” says Oskar Jenni of the University of Zurich (UZH).

In northeastern Switzerland, one secondary school tried a different approach. At the Gossau Upper Secondary School in the canton of St. Gallen, students began working with a flexible schedule that let them shape when their day began.

Instead of one fixed start time, students could attend optional modules before regular classes, at midday, or in the afternoon. That structure allowed a real choice: arrive at 7:30 a.m., or start at 8:30 a.m. when classes officially begin.

Researchers Joëlle Albrecht, Reto Huber and Jenni, from the University of Zurich and the University Children’s Hospital Zurich, studied what happened when that option became part of everyday school life. They surveyed students once under the old model, when the first lesson started at 7:20 a.m., and again a year later after the flexible model began.

They analyzed 754 survey responses in total. The preassessment included 351 of 407 students (an 85.6% participation rate). The postassessment included 403 of 410 students (98.5%). A subset of 212 students could be paired across both surveys.

The most telling result was simple behavior. Given the choice, students used it.

Ninety-five percent took advantage of the later start option. On average, they began school 38 minutes later than before. That translated into wake-up times about 40 minutes later on school days.

Bedtime did not shift in a meaningful way. Students still went to sleep around the same time, so the later mornings turned into more rest. On school days, total sleep increased by an average of 45 minutes.

Lead author Joëlle Albrecht sums up a key change in how students felt at night: “The students reported fewer problems falling asleep, and health-related quality of life increased ,” she says.

Not everything moved in the same direction. In the larger dataset, daytime sleepiness did not change significantly, and neither did problems staying asleep, caffeine intake, or the overall scores for health-related quality of life and depressive symptoms.

Still, the study found that the share of students reporting clinically relevant low levels of health-related quality of life fell from 25.1% at the earlier assessment to 17.1% later on, a statistically significant drop. Clinically relevant withdrawn or depressed symptom levels also fell, from 12.3% to 8.9%, though that change only “trended” toward significance.

The researchers place their findings in a broader context. They point to mounting concern about student mental health, and they argue that sleep remains one of the few levers schools can pull without asking teenagers to fight their own biology every night.

“Starting classes later in the morning can therefore significantly contribute to addressing the current mental health crisis among pupils,” says co-author Reto Huber.

The study also cites a 2022 report from the Swiss Health Observatory (Obsan) that found 47% of 11- to 15-year-olds experienced multiple recurring or chronic psycho-affective complaints, including sadness, fatigue, anxiety, low mood, tension, irritability, anger and difficulty falling asleep.

That does not mean a later start is a cure for adolescent distress. It does mean sleep fits into a real-world picture that schools already confront.

The researchers also looked at performance. Report-card grades in German, English and math did not change significantly between the two assessments.

Standardized test scores did. In the subset of students who took those tests, math scores improved in the later assessment, as did English. German and French standardized tests did not show significant changes.

The study, published in the Journal of Adolescent Health, describes the flexible model as a practical way to cut chronic sleep deprivation without cutting courses. Students did not take fewer elective classes overall.

Still, the paper is careful about what it can and cannot prove. The new school model included more than flexible start times. It also introduced adaptable learning formats and closer guidance in learning teams to promote independence and motivation. Those elements could have affected health or performance too.

Age also complicates the picture. Students were mostly 13 to 15 years old, with a median age of 14, and they aged by a year between surveys. The study had no control group, so it could not separate the effects of the schedule from typical developmental changes.

The paired sample also left out some older students, because third graders graduated and could not be followed up. That matters, since the researchers note that sleep phase preference tends to delay further with age, so older adolescents might benefit even more.

Finally, most measures came from self-report. The authors note that future work should add objective tools such as actigraphy.

Research findings are available online in the Journal of Adolescent Health.

The original story "The hidden cost of early morning classes on teen student brains" is published in The Brighter Side of News.

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