The B-Society is based on the research field of Chronobiology. The leading researcher within chronobiology is Till Roenneberg from Ludwig-Maximilians-Universität in Munich. He has mapped out more than 220,000 people’s circadian rhythms, which he has described in the book Internal Time, published at Harvard University Press in 2012. You can test your circadian rhythm at


Human beings have distinct circadian rhythms. A circadian rhythm indicates when the human being prefers to be awake and when the preference is for sleep. Our circadian rhythm is genetically determined, and it also can change during our life time. Research shows that our circadian rhythm is controlled by so-called “clock genes.” In 2003 the English researcher Dr. Simon N. Archer discovered that the late risers have a short version of the so-called Per3-gene. It is the Per3-gene, which controls when the body is programmed to be awake. The gene exists in two sizes, and it is the shorter gene that is found more frequently among late risers than early risers. Almost all teenagers are shifting their day and prefer to go to bed later and get up later, and when we get older we wake up earlier and earlier – often against our will. 


The distribution of circadian rhythms (chronotypes) ranges from people preferring to rise extremely early (early chronotypes) to people preferring to go to bed extremely late (late chronotypes), just like the human being ranges from being very tall to very short. An early chronotype is often awake between 6 AM and 10 PM and is most energetic in the morning and before noon. The late chronotype on the other hand is most energetic in the afternoon and in the evening and can for example be awake between 9 AM and 1 AM.

If an A-person (early chronotype) and a B-person (late chronotype) are going to bed at the same time and get up at the same early time, then they will be experiencing the mornings differently, as the body temperature of the early riser will be higher than that of the late riser at this time of the day. An early hour of rising will be experienced as though it was still the “chronobiological night-time” by the late chronotype – so there is a fundamental physiological reason why the late chronotype may feel low energy and low spirits in the early morning. 


At the University of Zurich a group of researchers headed by Steven Brown carry out research about how to map the individual biological rhythm of the human being. Our biological clock, which is controlled by 10,000 nerve cells in our brain, activates a special gene in our skin cells during the day. Utilizing this, the Swiss researchers succeeded in developing very precise measurements of the activity patterns for each of the subjects in the trial.  

The study showed that there were large differences between the activity patterns of early risers and late risers. Among approximately half of the participants in the study, the natural biological rhythms were more or less out of step, and these same participants often reported suffering with problems of insomnia or insufficient ability to concentrate on a task. The study documented that many people would work better and more productively if they could work at hours other than those ordinarily required, i.e. the traditional 8 or 9 AM to 4 or 5 PM. 


Teenagers are not lazy. One of the reasons why many children’s circadian rhythms are changing during puberty is that the brain and the body go through an enormous development in this period. The changes create increased fatigue in the morning and more energy in the evening. During youth, it may be difficult to fall asleep even though the young person may be lacking sleep. This unfortunately has negative effects upon their educational and developmental processes. Lack of sleep can lead to a chain reaction of obstacles in the everyday life: The young person is not only in low spirits and absent-minded during the morning lessons in school, they also encounter problems with concentration, learning difficulties, and mood swings. 

Teenagers need 8-10 hours of sleep every day, and a Norwegian study has shown that one out of twelve high school students suffer from lack of sleep. This can have a very negative impact on the health of the young persons. A study from the University of Kentucky in Lexington shows that by moving the time when school begins one hour the share of students getting at least eight hours sleep per night increases from 37.5 percent to 50 percent. Moreover, the students are more highly motivated, experience improved ability to concentrate, perform better in school, and maintain better eating habits. 


A German study carried out by Christoph Randler from the University of Heidelberg has compared students’ circadian rhythm with their grades in school. The results are discouraging. Late chronotypes achieve lower examination results because exams are often placed before noon. Too many young people therefore obtain results lower than their potential simply due to the fact that during puberty they are changing from being early peak-performers to late peak-performers. Studies have shown that a majority of students get better grades when participating in exams given in the afternoon, rather than when participating in exams that take place before noon. 


A Norwegian study carried out by Bjørn Bjorvatn shows that by beginning class at 9:30 AM on Mondays the students got an extra hour of sleep Sunday night, which resulted in better performance and reaction time. 

A Turkish study carried out by Senol Besoluk shows that the times of day that teaching and examination take place has a great impact on students’ performance. There is an unexploited potential in letting teenagers get enough sleep in accordance with the biological needs of their natural circadian rhythm. 

A study of approximately 2,000 pupils in the Swedish towns Luleå, Gävle and Jönköping shows that 13 percent of pupils in the 7th grade were distinctly early risers while 34 percent were distinctly late risers. In the 9th grade, fully half of the pupils were B-persons. 

In Denmark Vorbasse School has introduced flexible hours for the 7th, 8th and 9th graders. The pupils can themselves choose between working in teams between 8-10 AM or 2-4 PM. In this way, the pupils can be taught during the hours that best match their circadian rhythm. After the introduction of differentiated learning hours Vorbasse School has obtained measurable results. The average grade has gone up from 6.1 to 6.7, and the pupils are more alert and motivated when they receive training. At Egaa Ungdomshoejskole the superintendent Ulla Fisker has moved meeting time from 8:30 AM to 10 AM. This has resulted in students being more awake and alert so that they are more “learning-ready” students. 

At Frederiksberg Ny Skole in Denmark flexible hours are introduced from the very first year at school. The pupils have the possibility of be
ing taught at the hours that best match their different circadian rhythms. Children who are early risers can get intensive education in the morning between 8 and 9, whereas children who are late risers can be offered more intensive teaching between 1 and 2 in the afternoon. From the 7th grade it makes sense to differentiate even more, so that early risers can get intensive education between 8 and 10 in the morning, and late risers are taught more intensively between 2 and 4 in the afternoon. 

There is a paucity of research on the circadian rhythm of children. In the study of circadian rhythms children are described as early chronotypes, but there are more and more examples of children who are late chronotypes. This indicates a need for more research concerning the circadian rhythm of children, so that we may understand what time of the day is most beneficial for teaching children between the ages of 5 and 10. 


Unfortunately society is still organised to fit the early chronotypes and the people who prefer to work beginning early in the morning. This is also true for kindergartens, schools, and work places. 

A society that dictates early morning working hours for everyone will cause health problems for late chronotypes. Circadian rhythm and well-being are closely connected. Late chronotypes are generally consuming more invigorating stimuli like coffee and sugar than early risers in an attempt to fit into the dictated working time. Other downsides include the attempts of late chronotypes to ease stress with substances like nicotine or alcohol, or to use various medications in the quest to get enough sleep. Additionally, the alienation due to feelings of not fitting into the work schedule can lead to stress and stress-related illnesses. Furthermore, it is observed that late risers between the age of 31 and 40 have an increased risk of developing depression disorders.