Due to the internal biological clock, most children are not able to concentrate enough from 8 a.m. to acquire knowledge effectively. School should start later!
- According to the researchers, it is worth considering giving up early working hours or school classes. In their opinion, our brain is not designed to work so hard at such early hours
- The appeals to start classes later are getting louder, but – as with the discussions about switching from summer to winter time – it seems that the divisions between supporters and opponents have deepened recently
- Scientists who evaluate its impact on our life and health have just been awarded the Nobel Prize
The appeals to start classes later are getting louder, but, as with the discussions about switching from summer to winter time, it seems that the divisions between supporters and opponents have deepened recently. I have just come back from the WorldSleep conference in Prague, where the topic of school start time was featured in many lectures. Sleep researchers and their scientific cousins - chronobiologists – on our circadian cycle have long insisted on a revision of the principle of early start of lessons. In this confrontation, statements of a general nature are of little help. Rather, it is necessary to precisely define the hours and age group we are talking about, and to understand the scientific basis of certain phenomena. This applies especially to the circadian rhythm – the field of research for which the Nobel Prize in Medicine was awarded this year.
Why do we need a biological clock?
All the processes taking place in our body – body temperature, pulse, blood pressure, hormones, but also how quickly we count and absorb knowledge, and finally, when we sleep best – is regulated by the circadian rhythm. It positions itself actively, based on light and darkness, 24 hours a day. At the same time, the official time of these fundamental biological processes is not of interest, as their task is to adapt us optimally to the external rhythm of nature and – even more importantly – to changing conditions. So it precisely adjusts to optimal feeding and sleep times, while anticipating the threat of enemies or the advent of cold nights – even if in modern society all these factors do not seem as important as a few centuries earlier.
The internal clock has no idea that we are playing with the official clock by introducing daylight saving time, or that the inhabitants of northwestern Spain live in the astronomically proper time zone of Prague, Czech Republic. This clock, however, knows the intensity of light in the environment, because thanks to special receptors it measures it accurately and transmits the information obtained in this way to specific centers of the brain. Our brain has “learned” over millions of years that it gets up to 150 lux a day, and that at night there is deep darkness – except for the light of the fire, the moon and the stars.
Except that these conditions have fundamentally changed. During the day, we get maybe 400 lux, because we are hardly outside, and at night we disperse the darkness with electric light. Under these new conditions, our internal clock is doing just fine, except that it changes the rhythm of the day and night – delaying it for most people.
Since, however, as a result of industrialization, our social obligations did not shift to later, more than 80 percent. people need an alarm clock today to wake up on time. Nevertheless, the internal clock still decides what time we can fall asleep – definitely too late to sleep until the alarm clock rings. For some people, the internal clock has even stopped synchronizing with the 24-hour circadian rhythm. Chronobiologists call such people “non-24”. They must function in a 25-hour society with their approximately 24-hour rhythm. This is the opposite of the situation faced by shift workers whose 24-hour rhythm is pressed into non-24-hour working days.
It all depends on the light?
My colleague Ken Wright from the University of Colorado has proven that all these drastic changes are dependent on light. He took normal people living according to the modern circadian rhythm – that is, with a delayed internal clock – for a week’s camping in the Rocky Mountains. He measured them, among other things, the level of melatonin. While in urban conditions, before hiking in the mountains, this hormone gave them a signal to sleep around midnight, in natural light conditions this moment shifted many hours earlier, closer to sunset.
Due to this dependence on light, within one time zone, the rhythm of sleep and awakening moves from east to west about four minutes later for each degree of longitude. As a result, social life in Hungary takes place earlier than in Germany, and in West Germany itself, in the east of the country, earlier than in the west (and this has nothing to do with the heritage of the GDR), in France later than in Germany, and in Spain even later. Our ignorance of the rules described makes us think that the Spaniards leave the city late for purely cultural reasons, because no one sits down at 21:30 until supper here. Only that according to the astronomical time, it is then 19 o’clock in them!
Our internal circadian rhythm depends primarily on the light conditions. It cannot be consciously regulated or taught through discipline – nevertheless, due to more light during the day and greater darkness at night, you can fall asleep at the right time and wake up without an alarm clock. However, the circadian rhythm is not only determined by lighting, it also changes with age. In children, the internal clock is ahead of official time, but during adolescence it shifts sharply later, reaching its peak “late” around the age of 20. Then it gradually recedes again to wake us at an advanced age in the pale dawn. The described relationships of the circadian rhythm with age were confirmed in all the communities studied so far, also among people living without electricity.
What can be changed?
The team is studying the circadian rhythm of a tribe in Brazil, and I spend a few days with them myself. The only members of the community who sit around the fire late and have to be awakened by their parents after sunrise are teenagers. And this despite the lack of smartphones, TV sets or discos! Who if who, but older people should understand best that the circadian rhythm of adolescents cannot simply be reprogrammed. The recommendation, “Grandpa, sleep until 9” is as unrealistic as “Teen, go to sleep at 21”. The eternal biological clock will not allow this.
Understanding these phenomena must not only lead to discussions about school working hours, but also to a change in existing practices. Starting classes too early drastically reduces the ability of young people to learn. At exactly what time, according to their bodies, corresponds to midnight, they have to get up, focus on the lesson, speak – and they are deprived of exactly the period of sleep that is responsible for memorizing the material they have learned.
This has serious consequences especially for young people who have a so-called “late” chronotype, as it has been proven that they receive worse grades. For example, we are depriving them of a place at medical studies, although they are not stupid or lazier than the Friday high school graduates, to whom we grant these places. This is a completely absurd situation, comparable to the principle according to which we would not accept young people with scoliosis to study law because they failed the stick test. I have been waiting for a long time for a precedent court ruling that would legally prohibit such discrimination.
There are also many studies analyzing the effects of shifting the starting time from 8 to 9 and reporting the positive effects of such a decision: students were not only more motivated, but also less likely to miss classes while achieving better learning results.
* Professor Till Roenneberg is the chair of Human Chronobiology at the Institute of Medical Psychology at the Ludwig and Maximilian University of Munich.