Researchers at the University of Zurich studied whether giving teenagers flexibility in when they start school could help them sleep more. The question was simple: if students could choose between arriving at 7:30am or 8:30am, would they sleep better? The study followed 754 Swiss teenagers (average age 14) before and after their school introduced flexible start times three years ago.
The biological reason behind the question is clear. During the teen years, the body's internal clock naturally shifts later—teenagers genuinely feel alert later at night than adults do. This isn't laziness; it's biology. When schools start very early, many teens cannot fall asleep early enough the night before to get adequate rest, and this sleep debt builds throughout the week.
Nearly all teens chose the later option—and actually used it
When given freedom to attend optional morning modules or wait until 8:30am for regular classes to begin, 95% of students chose to start their day later. On average, they began school 38 minutes later than under the previous fixed schedule. Importantly, this wasn't just a survey preference—students actually woke up about 40 minutes later in the mornings.
More sleep led directly to better health and well-being
Because students' bedtimes stayed largely the same, the later wake-up time translated directly into more sleep. On school days, teenagers slept an average of 45 minutes longer than before the schedule change. Students also reported improvements in sleep quality and overall well-being. Since the study tracked the same students before and after the change, the connection between flexible start times and better sleep is reasonably clear, though the research was conducted in one Swiss school only.
Sleep deprivation affects far more than tiredness
According to Oskar Jenni, a developmental pediatrician at the University of Zurich, chronic sleep deprivation in teenagers impacts mental health, physical development, and learning ability—not just how they feel in the morning. The study shows that a modest shift in school timing can address this serious issue when students are allowed to choose what works with their biology.
- Advocate for flexible school start times in your teen's school, showing that 95% of students choose later starts when available.
- Recognise that your teen's difficulty falling asleep early is biological, not a discipline issue requiring earlier bedtimes.
- Monitor your teen's sleep duration during exam periods, aiming for the 45 extra minutes this study found beneficial.