Teens sleep longer and perform better when school starts later

As the week goes on, the problem often worsens. Most teenagers already start the week short on sleep, and the ongoing mismatch between their biological rhythms and early school schedules causes sleep deprivation to accumulate over several days.

“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). Jenni, a developmental pediatrician, explains that teenagers’ natural sleep patterns prevent them from going to bed early enough to meet their sleep needs. Allowing school to start later in the morning could therefore offer meaningful benefits. Although the advantages of later start times have been examined in many countries, fewer studies have looked at flexible systems that let students choose between earlier or later start times.

Testing Flexible School Start Times

Joëlle Albrecht, Reto Huber and Oskar Jenni from the University of Zurich and the University Children’s Hospital Zurich recently investigated whether more flexible schedules could better match teenagers’ biological rhythms. Their research focused on Gossau Upper Secondary School in the northeastern canton of St. Gallen, which introduced flexible school hours three years ago.

Under this system, students can attend optional learning modules before the official start of regular classes in the morning, during midday breaks, or later in the afternoon. This approach allows students to decide when to begin their school day. They can arrive as early as 7:30am or start at 8:30am, when regular classes begin.

Researchers used this schedule change to examine how sleep patterns and sleep deprivation affected students’ health and academic outcomes. The students, whose average age was 14, completed surveys twice. The first survey took place under the previous schedule, when school began at 7:20am. The second survey was conducted a year later after the flexible system had been introduced. In total, the research team analyzed 754 responses.

Flexible Schedules Lead to More Sleep

The results were clear. Ninety five percent of students chose to begin school later when given the option. On average, they started their day 38 minutes later than under the earlier schedule.

As a result, students woke up about 40 minutes later in the morning. Because their bedtimes remained largely unchanged, the later wake up time translated directly into more sleep. On school days, the teenagers slept an average of 45 minutes longer than before.

Students also reported improvements in sleep quality and overall well being. “The students reported fewer problems falling asleep, and health-related quality of life increased,” summarizes lead author Joëlle Albrecht. Academic performance improved as well. Compared with cantonal test results, students achieved better outcomes in English and mathematics after the schedule change.

Better Sleep Supports Teen Health and Learning

The findings, published in the Journal of Adolescent Health, suggest that flexible school start times could be a practical way to reduce chronic sleep deprivation among teenagers. The results also point to improvements in mental health and academic performance when school schedules better match adolescents’ biological rhythms.

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

Concerns about youth mental health are widespread. In 2022, a report from the Swiss Health Observatory (Obsan) found that 47% of 11 to 15 year olds experienced recurring or chronic psycho-affective symptoms. These included sadness, fatigue, anxiety, low mood, tension, irritability, anger and difficulty falling asleep.