Should lessons for young people start later?
The internal clock, also known as the circadian rhythm, generally ticks differently in adolescents than in older or younger people. Their bodies signal to teenagers that they should stay up later and get up later. This means that it is difficult for them if they have to do school work early in the morning.
Various pilot projects have shown that starting lessons later in secondary school can help pupils to sleep more, feel less depressed, have fewer absences and achieve better grades. One school, for example, changed the already relatively late start of lessons at 8.50am to 10am. As a result, 12 per cent more pupils achieved «good academic progress» and the average number of sick days fell from 15 to 11.
However, the chronotypes - the natural preference for sleeping and waking rhythms - of adolescents are just as different as those of adults. The «owls» prefer to sleep longer, while the «larks» like to go to bed early. Teenagers, who are most likely to perform poorly at school if they start school early, tend to have a predisposition to be owls. Larks, on the other hand, tend to perform at their best. This means that starting lessons later would be helpful for owls, but useless or even detrimental for larks.
What influence does the time of the start of lessons have?
However, there is a problem with the evidence: most of the studies designed to distinguish the effect of chronotypes and the start of lessons were not randomised.
«Children - or at least their parents - usually choose a school with a timing that they themselves prefer,» says Guadalupe Rodriguez Ferrante from the neuroscience laboratory at the Universidad Torcuato di Tella in Buenos Aires, Argentina. She recently co-authored a study on adolescent chronotypes and class times. «If you're an owl, you might choose an afternoon school. This leads to a bias in the study results.» In this case, the chronotype could have less of an impact on grades and absences than in a school model in which pupils are randomly assigned to a lesson start time.
Among other things, this makes it difficult to distinguish whether owls perform worse because their chronotype does not match the lesson time, or whether certain characteristics of this chronotype are responsible for the poorer performance.
Rodriguez Ferrante investigated this question at a secondary school in Buenos Aires, which offers three different times for the start of lessons. The 259 pupils who took part in the study were randomly allocated to the following times for the start of lessons: 7.45 a.m., 12.40 p.m. or 5.20 p.m. Their chronotypes were determined using a questionnaire and the results from the first and fifth school years were analysed.
On average, female pupils whose lessons started later performed better at school.
Shift in rhythm during puberty
It is particularly interesting to study chronotypes and the start of lessons in Buenos Aires, explains Rodriguez Ferrante, because «people in Argentina tend to belong to a very, very late chronotype. We eat dinner at 10 pm. But secondary school usually starts at 7.30 or 7.45».
Many of her team's study results support the findings of other studies. On average, female pupils whose lessons started later performed better at school. However, this changed as the pupils got older. There were also differences in the school subjects. For example, female pupils in the first year of school (13 to 14 years) who attended afternoon lessons achieved better maths grades on average than pupils who attended morning or evening lessons. In the fifth and final school year (17 to 18 years), however, the female students in the evening classes achieved better maths grades than their peers in the earlier classes. This could indicate a possible shift in the circadian rhythm during puberty, write Rodriguez Ferrante and her co-authors.
Interestingly, this pattern was not evident in language lessons. The grades there were better than in maths, although the differences between the groups with different lesson times were smaller. However, to find out whether there is an effect at all, a study with a larger number of participants would have to be carried out.
As expected, the performance of the owls in the morning lessons was worse than that of the larks. Pupils were more likely to make the transition to the next level at the end of the school year if their chronotype and the start of lessons matched.
Why owls perform worse than larks
Among the older female students, the performance in maths was worse among the owls than among the larks in the same class, regardless of the start of the lesson. This indicates that it is not only the discrepancy between chronotype and start of lessons that is responsible for the negative effect on performance (although, according to Rodriguez Ferrante, the difference was greatest in the morning lessons). Rather, there could be something else behind it.
The poorer performance of the owls could be due to the fact that they simply sleep less. On school days, fifth-year pupils who had lessons in the morning slept less than six hours a night on average. But around 16 per cent of female pupils slept only four and a half hours or even less. Although the researchers have not yet confirmed whether the second group was more likely to be owls, according to Rodriguez Ferrante, people with a later chronotype often sleep less overall.
For the vast majority of young people, school simply starts too early.
Even though the study was conducted randomly, the results could be influenced by this, says Rodriguez Ferrante. The widespread belief that someone who goes to bed late and wakes up late is lazy could lead to teachers unconsciously giving better grades to students in the morning class than to students in the evening class. Or pupils themselves may reflect these prejudices - owls may believe that it is pointless to make an effort because they are lazy.
«It's really difficult to tell this apart,» says Rodriguez Ferrante. «We need to further investigate the relationship between chronotype, the start of lessons and academic performance. I really want to find out which mechanisms influence the performance of a chronotype. Is it the pupils' self-perception? How is that connected?»
Nevertheless, according to Rodriguez Ferrante, the results are clear: for the vast majority of young people, school simply starts too early. «Change is not easy. You have to reach the politicians,» she says, «and that means gathering as much research data as possible so that we can really have a positive impact on young people's lives.»
This text first appeared in English on the BOLD platform.
