Chronobiology: what is it and why is it important?

Chronobiologie: Was ist das und wofür ist sie wichtig?

The best day after a hard day is when you can lie down in your bed and know that you can sleep peacefully. But what happens when you lie in bed and just can't get to sleep.

Your body clock just goes "crazy" and you know that you'll wake up at 6 the next morning no matter what time you go to sleep. Chronobiology deals with your internal clock and other phenomena. In the following we will explain the most important information and facts about chronobiology to you.

the essentials in brief

  • Chronobiology deals with the cycles of the human body
  • Among other things, you can be categorized as either a lark or an owl based on your internal clock
  • The biorhythm or the inner clock is responsible for many important processes in the body, such as food intake or the elimination of melatonin.

Background: what is chronobiology?

Chronobiology is a branch of biology, but nevertheless very versatile. So that you are not overwhelmed with information, we have put together all the facts and questions for you here. With this we hope to give you a good and clear overview of the topic.

What does chronobiology mean?

Chronobiology is a branch of biology that aims to study the nature of the natural cycles of a human body. The main focus is on how the body is influenced on the emotional, physical and mental levels due to the sun and moon rhythms.

Thus, chronobiology also includes the inner clock.

What is meant by this is that our body cannot escape the day and night rhythms. Among other things, it is due to the fact that the change between light and darkness has accompanied us since the emergence of mankind. Our body is guided by genetically manifested zeitgebers, which, among other things, are very deeply anchored in our being. (1,2)

There are three cycles that have been divided into. These are called Infradian Rhythms, Ultradian Rhythms and the last one the Circadian Rhythms. Infradiane is a rhythm that lasts longer than 24 hours and is rarely repeated. Either every few days, weeks or months, even as little as once a year this can be the case.

Ultradians are rhythms that last less than 24 hours and can occur repeatedly within a day. They usually regulate the physical, mental and emotional functions of the human body, such as the cycle of food intake or hormone release or blood circulation. In adults, a cycle of relaxation and contraction occurs about every two hours.

The final cycle is the circadian rhythm. These last about 24 hours, affect people more immediately or directly and are thus to be understood, for example, as comparatively the leaf movement in plants or the sleep-wake cycle in humans. (3)

What chronotypes are there?

The categories under which a person is classified based on their internal clock is called the chronotype. The types have different physical characteristics such as hormone levels, sleep-wake phases, performance and body temperatures, which we have at different times of the day and in different conditions. In the table below we have listed the chronotypes for you. (4.5)

chronotype Characteristics
extreme early type Sleeps from about 9pm to 5am/ 10pm to 6am. The proportion of the population is around 1%
moderate early type Sleeps from about 11pm to 7am. The proportion of the population is between 4-10%
easy early type Sleeps from about 12:00 a.m. to 8:00 a.m. The proportion of the population that counts is 15-17%
normal type Sleeps from about 1am to 9am. The proportion of the population is between 12-16%
light late type Sleeps from about 2am to 10am. The proportion of the population is between 7-9%
moderate late type Sleeps from about 3am to 11am. The proportion of the population is between 2-4%
extreme late type Sleeps from about 5am to 1pm. The proportion of the population is less than 1%


However, it can be concluded that the majority of the population fall asleep around midnight and wake up around 9am. However, this does not include normal work or school life. Most of them have to get up earlier.

How do I know if I'm an owl or a lark?

A lark is a colloquial term for a person who is more of a morning type. So if you are an early type (extreme or moderate) you can assume or call yourself a lark. The special characteristics are that you not only get up early in the morning but are also wide awake. The probability is also very high that you will find it difficult to keep your eyes open after 9 p.m. in the evening.

So if you belong to the lark category, you are in your best mental form in the morning and deliver your best athletic performance in the early afternoon. However, keep in mind that as a lark, you will most likely have it worse after a party or concert. Your body clock usually wakes you up the next morning as early as usual.

owl or lark

So it can't hurt to find out if you're more of an owl or a lark. Knowing your type can do you a lot of good. (Image Source: James Toose / unsplash)

So an owl is more colloquial for you being an evening type. Most people find it difficult to get up early in the morning as an owl. You are therefore still in the "low". The same applies here to your digestive tract. This is not “active” in the morning itself, which is why your breakfast can be awkward in your stomach.

However, as a late type you often have your mental high when most people are going through their low of the day. This is also one of the reasons why you tend to go to the gym in the evenings, because only then can you deliver your best athletic performance. (7)

What does it mean for me to have an internal clock and what influences it?

Basically, the inner clock is different for everyone. It ensures that each of us "ticks" individually. However, the internal clock cannot be adjusted and cannot be corrupted. However, there are exceptions such as children are more likely to be larks and when they reach puberty they become owls.

It is genetic in every human being.

The internal clock depends on various influencing factors. One of these is the sleep-wake cycle, sleep itself and the change from light to dark during the day. However, it is emphasized that the internal clock and sleep are not fundamentally the same, but that one influences the other.

This means the following. Sleep itself is a process or an achievement that your body accomplishes, while the internal clock is a property that every cell in your body carries within itself. The process takes place as follows. Our cells have clock genes in them, and these determine when certain information or stimuli are turned on and off. The information we take in with our eyes helps us to do this.

The clock genes are also there to control the effects of common medication or vitamins. Because our eyes can also sense the time of day, the environment, and even the seasons of the year, these two characteristics form the basic building block of how our body clock works.

Due to the stimuli that we absorb, such as the day-night cycle, our body coordinates them with several rhythms of our body either simultaneously with each other and with each other. Light itself therefore plays a very important role. (8th)

How important is a biorhythm?

Biorhythm, also known as the cycle of our body, is not only characterized by continuous and recurring cycles of natural fluctuations in bodily functions and their ongoing changes. This is very important for our body and our health.

This is partly because it tells our body, for example, when it should work and be active and when it can switch off or be a little more relaxed. The biorhythm not only influences certain functions in the body, there are even risks if you don't listen to your internal clock. We have listed this information for you in the following table:

information about factors
general influence Blood pressure, body temperatures, hormone balance, food intake and drinking rhythm
general risks Insomnia, depression, mood swings

However, among these risks there is a special type called social jet lag. Before industrialization, our bodies and internal clocks were based on the sundial. Our body got a lot of light, which was good. Because the “social clock” (hence the name) came about, our lives were adjusted accordingly. (9,10,11)

The focus was no longer on the day and night rhythm as before. He has tuned in to our alarm clock. It doesn't matter whether it's dark or light outside, because when the alarm clock rings, we get up. As a result, many activities take place indoors and our body gets less sunlight.

Other risks would also be a higher smoking rate and increased alcohol consumption.

However, the risks are worse for owls because they have to get up early but stay up later. You try to catch up on sleep on weekends and it's not good for your body. By ignoring the internal clock, some risks arise, such as increased stress, depression, obesity and sleep apnea.

What is the best sleep pattern?

The best sleep pattern is different for everyone. It would be important to find out which chronotype you are in order to know your inner clock. Basically, when it comes to sleep, it is more important that you have a rested and good quality sleep than the duration. Short sleepers may only need five to six hours, while late sleepers may need nine or more.

Too little sleep can be harmful to you, so don't tell yourself that your body will get used to it. Basically, the five hours of deep sleep are the most important for our recovery. Alarm clocks are rather negative for a healthy sleep rhythm. Because we are in different phases of sleep, an alarm clock can wake us from either deep sleep or light sleep.

Alarm clock

It's best not to set an alarm if you don't have an important appointment. This is the best way to get to know your inner clock and to act accordingly. (Image source: Julian Hochgesang / unsplash)

If we are woken up from deep sleep, we feel much more broken than from light sleep. The best sleep rhythm for everyone is therefore individual and dependent on the type. Our body knows how much sleep we need and it is best to get it to give our body the energy and rest it needs. (12)

What is a daily rhythm?

The daily rhythm is also controlled by the internal clock. However, this is also influenced by external zeitgebers. Basically, this means that in the morning between seven and nine o'clock our body tries to boost the metabolism and thus releases hormones.

From 10 a.m. to 12 p.m., our brain theoretically runs at full speed for the first time. From 12-14 is the digestion time for our body, which then comes along with the first low. From 3 p.m. to 6 p.m. there is the theoretical second high with a good learning phase. Then comes the relaxation phase and our bodies switch to recovery.

What is the sleep-wake cycle?

The sleep-wake cycle is very important for our body. Our inner clock sets the pace for us. The inner clock in our body controls, among other things, the release of the hormone melatonin and also allows other biochemical and psychological processes to run in a cycle.

Light is the most important component here. If you fight against your sleep-wake cycle, the following health problems could arise, such as a restricted ability to react, a weakened immune system, sleep disorders and reduced concentration and memory.


You can also put your bed against a wall where a window is in close proximity. So you get some sunlight early in the morning. (Image source: Gregory Pappas / unsplash)

If there is a change in your sleep-wake cycle, it can lead to you "screwing" your inner clock. Most often this happens on weekends when you change your sleeping habits. As a result, you tend to be listless and in a bad mood most of the time on Monday mornings.

Can I change my chronotype?

Basically, you can influence your internal clock to a certain extent and thus slightly change your chronotype. Our body is very fixated on the light. For example, the more sunlight that shines into a room, the earlier you wake up. The body is basically more diurnal because of the light. The more there is, the more awake your body feels. (13.14)

However, you should consider your individual sleep needs.

When it gets darker, our body adjusts accordingly and automatically becomes more tired. With enough sunlight, you can train your body to get up earlier without feeling tired. In this way you can harmonize your internal clock with the natural rhythm of the sun.


Basically, it is very important for us to know which chronotype we are and how our inner clock is ticking. This not only gives us positive effects in terms of our physical condition, but also mentally and emotionally.

It is therefore very important not to ignore it or want to change it too much, because this will lead to many risks. Reasons are that our internal clock is genetically predisposed and they are part of our cells. Thus, our chronotype determines much more and is very important for our state of mind.


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