How our internal clock changes with age?
Our circadian rhythm dictates our sleep patterns and those differ with age. If we have a look at newborn babies, they have a rhythm that cycles around sleeping, feeding, and growing, and this cycle repeats constantly for several months. This type of rhythm is much shorter than the 24h-cycle of most people (8 hours of sleep and 16 hours of activity on average).
The world-renowned expert of Chronobiology - professor Till Roenneberg, together with his team, has gathered one of the most extensive and comprehensive databases on sleep patterns ( unich Chronotype Questionnaire – MCTQ ).
The database provides an invaluable source of information on how our chronotypes (i.e. our personal propensity to sleep) change with age and the results of it are astonishing. According to the MCTQ, on average, young kids have early chronotypes, which explains why they are up and running during the day and why, once it becomes dark, they easily go to sleep.
At the time they reach their teen years, children start to have later chronotypes and usually become true night owls. That is one of the main reasons why we dreaded the early morning classes at high school, especially the ones that required us not only to listen, but also to solve complex problems – our brains were just still sleeping and not working properly at that time of the day!
People usually reach their chronotype’s turning point at the age of 19 (women) and 21 (men), and start to go back to being more early types than evening types.
On the graph you can see that teenage boys continue to delay their biological rhythms even after teenage girls have reached their turning point. That is why men, on average, have later chronotypes than women during the time when they are adults.
So, next time when we argue with our teenage children that discos and going out with friends late at night are the reason why they are so groggy in the morning, maybe we should think it twice. :)