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CHRONOTYPE: Understand the variations in our circadian rhythms


Think that you are on vacation, with no appointments scheduled and are free to plan your routine thinking only of your well-being. What time would you sleep at night? And what time would you wake up in the morning?


There are no correct answers to these questions. There are people who will prefer to sleep and wake up early; while others will sleep and wake up very late. Each one of us has a profile and a preference for times to wake up, sleep and carry out our activities. These variations in our preferences are called CHRONOTYPES!


In this blog we'll understand what chronotypes are, why people's time preferences vary so much and what the consequences are.

What is the chronotype?


The duration of the day on our planet is 24 hours and we have to synchronize all our biological activities and functions to that. This is why our entire physiology follows a circadian rhythm (ie about a day). The main one of these rhythms is the sleep-wake cycle. It is because of this cycle, very well orchestrated by our brain, that we tend to sleep at night and stay awake during the day, for our entire lives.


However, not all people sleep and wake up at the same time, and sleep-wake cycles vary somewhat between people. That's where the chronotypes are established.


Chronotypes are our circadian preference profiles. In general, we have three different chronotypes:


· Morning: These are people who prefer to sleep and wake up earlier than the average population. Morning people are generally more energetic and work better in the morning. These people may find it difficult to work at night.


· Evening: These are people who prefer to sleep and wake up later than the average population. Evening people are generally more energetic and work best in the late afternoon or early evening and may find it difficult to work early in the morning.


· Intermediaries: These are people whose sleeping, waking and working times are closer to the population average. These people generally have more flexibility to adapt their routine to changes, whether for activities sooner or later than usual.


A classic survey carried out by researchers at USP in 1990 determined the frequency of each chronotype among Brazilians. It was noted that most people are of the intermediate chronotype (49%), while 39% are morning and 12% are afternoon. Mornings and afternoons can be further divided into moderates and extremes.


It must be understood that chronotypes are not diseases! These circadian preference profiles are completely normal patterns and are very important to our physiology. They are so normal that they are determined by our DNA. This subject is so relevant that in 2017 the Nobel Prize in Medicine was given to researchers who discovered the genetic basis of circadian rhythms. One of these genes (called PERIOD – or PER) seems to be one of the main determinants of our chronotype.


Knowing that chronotypes are determined by our DNA, we can conclude something important: Nobody chooses their chronotype. Being morning or evening is simply a manifestation of our normal physiological rhythms.


Is it possible to change your chronotype?


It is normal for the chronotype to change throughout life. For example, it is common for teenagers to be more afternoon, but throughout adult life we ​​tend to revert to a more intermediate pattern. This evening tendency during adolescence and early adulthood is completely normal and physiological. The causes are still not very well understood, but possibly it has to do with a delay in the effect of melatonin around the age of 15 to 25 years.

So, parents understand: although limits must be set, it's natural for your teenagers to want to go to bed a little later and take longer to wake up. They're just manifesting their normal circadian physiology!


When we get older, the tendency is to get more and more morning. That's why grandpa and grandma like to wake up so early. They are also manifesting their normal sleep pattern.


Sometimes we want or need to change our chronotype to suit the society around us. Social, work and play activities can even change our schedule preferences a little; but they don't necessarily change our chronotype. For example, an 18-year-old afternoon young man will have to get up very early to go to college. As much as he manages to wake up early, it doesn't alter the physiology and genetics that determine our circadian rhythms. As much as he manages to wake up early to go to college, he will continue to be afternoon.


Problems associated with chronotype


We have already mentioned that chronotypes are natural manifestations of our physiology and that they are not diseases. Still, they can be associated with very serious problems.


Problems do not occur because of the chronotype itself, but when our chronotype is not synchronized with our social or work activities. This is much more common than it sounds. Below are some examples:

· An afternoon teenager who needs to wake up very early to go to school.

· A morning grandmother who needs to stay up late to take care of her grandchildren.

· A morning person who works as a night watchman.

· An afternoon bus driver, who starts driving at 6 am.


In all these conditions people cannot exercise their circadian preferences because they are incompatible with their functions or tasks. This condition is known as social jet lag, as it is as if our “internal clock” were always at a different pace from the society in which we live.


The first consequence of social jet lag is sleep deprivation and drowsiness. A person who cannot synchronize their circadian and social rhythms always ends up sleeping less than they would like. As a result, these people end up being very sleepy during the day. This is just the beginning of the problems... The next ones come in time.


The first consequences are usually cognitive and behavioral, including decreased attention, aggression, anxiety and depression symptoms. Over time, the common consequences of sleep deprivation come, such as increased risk for the development of hypertension, diabetes and other diseases. Finally, there are professional and social losses, which include increased risk of work and car accidents, decreased productivity at work and increased absenteeism and presenteeism. In addition to these, one of the most debated issues lately is the effects on teenagers' academic performance.


Decrease in academic performance and low grades


As we've already mentioned, teenagers and young adults tend to be in the afternoon. However, in Brazil and in many other countries there seems to be a contradiction in school hours. Elementary school children, who are easy to wake up early, tend to study in the afternoon, while teenagers in high school and college, who have a hard time waking up early, tend to have their classes in the morning.


This creates a very severe sleep deprivation condition among teenagers. They sleep later by biological tendency, but wake up very early because of their studies. Thus, afternoon teenagers arrive at class sleepy and with very reduced attention span.


Many initiatives have already been made so that teens and young adults' class schedules are delayed by a few hours, allowing them to get a little more sleep. In California, a law prohibits teen classes from starting before 8:30. In Brazil, many proposals have been made, although the implementation of these strategies is still a challenge. In places where it was possible to delay the start of classes, the results were always very good, leading to higher school performance, better grades, lower failure rates and a reduction in school dropout.


How to find your chronotype


The afternoon sleep pattern and insomnia are often confused, as the complaints and consequences of both are very similar. However, the treatment of sleep complaints may be different in these two cases. Therefore, it is very important that the chronotype is evaluated whenever possible.


The simplest way to assess your chronotype is to understand your sleeping times and preferences. For evenings and extreme mornings, this can be easily identifiable. But for moderate profiles, this assessment is too superficial and can lead to errors. The most appropriate way is to use validated tools and questionnaires to assess the chronotype.


SleepUp has a chronotype evaluation in its Standard and Premium plans. The results of this assessment are taken into account throughout the follow-up plan. Thus, we do our best to ensure that your chronotype is understood and respected!

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