The teenage German students who took part in this were better rested and more alert for their academics. Teenagers generally need more sleep than adults and many find it difficult to go to sleep at earlier hours — there is clearly a significant benefit to having high schools start at later hours.
Society is in the midst of an epic sleep deprivation crisis, and some of the most affected people are teenagers, a broad body of sleep research shows.
Because of this, in recent decades researchers in the US and around the world have been investigating the potential benefits of starting the school day later. While initial results are promising, it’s still only early days for this field of research overall, given the limited number (and nature) of experiments conducted so far.
To date, most studies in this area have looked at the effects of making a static change in school start time (starting all classes for a group of students an hour later, for example). But what happens if you give kids a say in the matter, letting them choose what time they begin classes in the morning?
That’s what one high school in Germany did. Alsdorf high school (Gymnasium Alsdorf) in western Germany won an award for innovative teaching methods in 2013, and practises an educational system called the Dalton Plan, originally developed in the US.
The Dalton Plan calls for flexible teaching methods, tailored to students at a personal level, and helping children to learn at their own pace. Schools across the world use these principles, and for chronobiology researchers at Ludwig Maximilian University of Munich, Alsdorf high school provided a unique chance to study how the system might be able to benefit sleep-deprived teenagers.
“We had the opportunity to study the effects of later school starting times when a high school in Germany decided to introduce flexible start times for their senior students,” the team, led by chronobiologist Till Roenneberg, explains in their paper.
“Instead of fixed starts at mostly 8 am, in this new flexible system, the senior students could decide whether to start at 8:00 am or at 8:50 am (referred to as ‘9 am’ herein for convenience) on a daily basis by attending or skipping the first period (a self-study period).”
For nine weeks in total in 2016, the researchers attempted to measure the effects of the system change on students in the 10th, 11th, and 12th grades.
While students in earlier grades still had to turn up for school at the standard time of 8 am, the older students were given the option of starting the day approximately one hour later for classes, in which case they had to make up the missed period (a self-study period) later in the week.
For the nine weeks (three prior to the system being introduced, and six weeks after the change), the researchers collected daily sleep diaries from the senior students taking part in the experiment, as well as collecting movement data from wrist-worn sleep monitor devices used by some of the students.
What the researchers found is that giving the students the ability to postpone their starting time even by only one hour gave them beneficial extra sleep time.
“In our study, virtually all participating students (97 percent) benefited from later start times, sleeping longer on schooldays with a ≥9 am-start – on average students gained one hour of sleep on those days,” the authors write.
“Importantly, not only was the overall benefit universal but also the magnitude of the benefit was similar across the important factors chronotype, gender, grade, and frequency of later starts.”
That’s an important finding, because even though it may seem obvious that students electing to attend school one hour later would get one hour more sleep, it’s also thought that later school times can encourage students to stay up later at night before school, negating the benefits of the sleep-in.
That didn’t happen here, though, with students on average sleeping 1.1 hours longer than they normally did on mornings where they attended classes later, increasing from 6.9 hours of sleep on average to 8 hours of sleep.
“One of the greatest concerns regarding later school starts is that teenagers might be tempted to stay up even later in the evening either consciously or via delayed circadian rhythms from later exposure to advancing morning light,” the authors explain.
“In our study, however, there was no evidence that sleep onset times differed between ≥9 am-days and 8 am-days.”
What did surprise the researchers was how little the students opted to take advantage of the late start. Overall, the students only chose to start late 39 percent of the time, roughly two days out of five in terms of a regular school week.
Nonetheless, when students did start later, they rated themselves as enjoying higher-quality sleep, and survey responses at the end of the experiment suggested they felt less tired, could concentrate better during class, and felt an improved ability to study at home after school as well.
Of course, all of those outcomes are self-reported, as were other data in the study, such as things like naps, which may have been non-declared or under-reported – limitations that the researchers acknowledge.
At the same time, there are obviously some hugely important takeaways from the experiment, which suggest students like being given the choice of when they start school in the morning (in addition to simply getting more shut-eye).
“On days with a later start, students have the opportunity to sleep longer. This should reduce the accumulation of sleep debt during the week,” the authors conclude.
“In addition, especially important for practical applications, students prefer the flexible system and their subjective parameters are improved.”
The findings are reported in Sleep.