He was so right, good old Kant, because sleeping badly precedes many illnesses and almost every mental illness is associated with sleep problems.

For example, sleeping poorly doubles the likelihood of developing depression or addiction in the following 5 years. However, problems with sleep also have genetic causes. People who have a certain mutation on the 7th chromosome (on the RFX3 gene) clearly have increased problems with insomnia. It is precisely this mutation that leads disproportionately often to depression as well as diabetes. The same is true for the MEIS1 gene, which is blamed not only for insomnia but also for restless legs syndrome. Both also show the close interconnection of insomnia and mental illness at the genetic level.

Like many diseases, the genetic predisposition to insomnia needs a trigger. Nowadays we find it everywhere: STRESS. Stress activates the so-called HPA (hypothalamic-pituitary-adrenal axis). In short (you can find the exact functioning here:) this causes a constant release of cortisol. As a result, the body is focused on stress response, which in turn causes insomnia. Tasks such as immune response, metabolism, cardiovascular system, concentration and learning performance are neglected. This leads to physical and mental illnesses such as high blood pressure, diabetes and Alzheimer’s disease, as well as a vulnerable immune system. The activity of our killer cells drops by almost 30% after just one sleepless night.
You see, sleep disorders should not be taken lightly. And there are enough people affected. In my practice, too, almost all clients suffer from sleep disorders.

If at night, I of Germany think / No sleep for me, awake I blink..?

Exactly, because Germany sleeps too little….

According to a study by the Techniker-Krankenkasse, more than half of those surveyed sleep 6h or less.

This is despite the fact that there are only about 2% of people who can manage with less than 6h of sleep, so-called short sleepers. 15% need more than 10h of sleep and are called long sleepers. So the average amount of sleep needed is between 6-9h. According to studies, this duration guarantees focused and active perception during the day. Less, but also more, is proven to limit the brain’s performance, especially with regard to verbal expression and logical thinking.

… and too badly,

20-30% of Germans occasionally to often have insomnia and as many as 40% are afraid of it. This has fatal consequences, not only for the individual, but also for the economy. It is estimated that around 200,000 working days are lost every year in Germany due to mental or physical absence caused by lack of sleep. At the same time, the number of sleep disorders is continuously increasing, by as much as 66% since 2010. The reasons have a lot to do with television and mobile phones, but partly also with stress-related mental carousels.

… which mainly affects women.

Overall, women’s sleep is much more prone to disturbances. This is mainly due to our biology. Women need to hear when their offspring are calling – even in the case of quiet sounds. Because of this maternal role, they also offer others a sense of security in the group. That’s why women sleep better when they sleep alone and men sleep worse. 😊

Excursus: The sleep phases and their effects.

Even if you’ve read this before, here’s a quick overview of the stages of our sleep.

Falling asleep phase:

In this phase, blood pressure already drops and breathing slows down. The body temperature lowers and we slowly drift into relaxation.

Light sleep phase:

In this phase, it is easy to wake up again, but the muscles are already relaxed and the eyelids are closed. You should know that we spend about 50% of the night in this phase.

Deep sleep phase:

Now all body functions are reduced to a minimum. Breathing is flat, the heartbeat is slow and the body temperature is low. This is the most important phase of sleep, because during this time numerous growth hormones are released to strengthen the immune system and regenerate the cells. During this phase of relaxation, the cell spacing in the brain increases. This allows waste products such as proteins to be transported away through the cerebrospinal fluid. This also explains why Alzheimer’s in particular is associated with poor sleep. Because this disease is characterised by the accumulation of protein clusters in the brain. In the deep sleep phase, the gap between the synapses of our brain also widens, which allows us to forget meaningless knowledge and thus create space for new things.

REM sleep phase:

This phase, which precedes waking, is important for processing emotional and procedural memories (something like driving a car, for example). What’s exciting is that we activate the same brainwaves here as we do when learning while awake. So our brain is actually learning while we sleep – from the experiences we have had.

These four phases are passed through several times during the night, and REM sleep occurs again after 60-90 minutes.

You are really well-rested when the deep sleep phases are of the same length as the REM sleep phases. Our body needs deep sleep most of all to ensure its physical existence – so it concentrates on it when sleep duration is shortened.

It is interesting that after only a few (approx. 10) days of poor sleep, people regard this state as normal and no longer attribute their irritability and lack of performance to poor sleep.

How does the body know when it’s time for sleeping?

This has to do with our biological clock, …

All life on our planet follows the 24-hour rhythm determined by daylight in some form or another (you can find out more about how this works here). In humans, this biological clock is organised by the suprachiasmatic nucleus (SCN), a collection of about 50,000 neurons in the anterior hypothalamus. The profundity of this daylight-oriented rhythm is shown by the fact that a single one of these neurons continues to maintain the 24h rhythm even when viewed separately in the laboratory. However, this nucleus is not solely responsible for our biological clock. In isolated cells from almost every organ of our body, clock genes could also be detected, which means that the suprachiasmatic nucleus is only the organiser of all these organ clocks. Incidentally, this also explains jet lag – it takes time for the SCN to get the organ clocks, which now run differently, back in tune with each other.

In order to keep our body in this 24-hour rhythm, our eyes must be able to perceive the correspondingly changing light conditions of a natural earth day. This is not done by our rods and cones, but by special photoreceptors which are not located in the eye, but on the optic nerve. This indicates that these are extremely old structures that existed before the development of a sense of sight. This means that even blind people can perceive light to the extent that they are able to maintain the 24-hour rhythm. Incidentally, these cells react particularly intensively to blue light, which illustrates how much the influence of electronic devices with blue light radiation can upset our biological rhythm.

… which does not work in exactly the same way for everyone.

In some people – for genetic reasons – they run a little faster, in others a little slower. This difference changes over a person’s lifetime. While it runs faster in children, it slows down during puberty and only in old age does it return to the speed it had when it was a child. However, this shift is not the same for all people – the so-called larks have a faster-running clock than the owls. Hormones also have an effect on our biorhythms. (A beautiful illustration of the organ clock including the activities recommended at the times you can find here or here.) In particular, there are considerable differences between women and men – women, for example, sober up best at three in the afternoon, men at seven in the morning.

Incidentally, this change in the course of the biological clock makes the early school starting times less effective, and this effect is further intensified by the summer time. Research has shown that pupils show an increase in performance during the day, which is obviously also hormonally controlled, while teachers show a drop in performance during the same period.

Furthermore, hormones give the signals for sleeping and waking….


Like our organs are active differently at different times of the day, there are also different concentrations of the hormones and neurotransmitters important for sleep at different times. Melatonin, known as the “sleep hormone”, which is produced through the conversion of serotonin when it is dark, is mainly produced in the pineal gland of the brain. As dusk begins to fall, production increases and peaks around 3 h at night. Our body’s melatonin production changes with age – while it reaches its peak in small children, it drops sharply with age, so that older people in particular have problems falling asleep and staying asleep.


As melatonin levels drop at rise time, cortisol, as melatonin’s counterpart, takes over the task of keeping us awake through the day. We have the highest cortisol level in the morning after getting up. Unfortunately, the cortisol cycle with its evening decrease only works in a comparatively stress-free life. Under constant stress, the cortisol level does not decrease sufficiently in the evening and thereby forms an obstacle to melatonin production and thus to relaxed falling asleep and sleeping through the night.


The neurotransmitter serotonin is the essential starting point for melatonin production in the body. Sunlight stimulates its production. The basic substances needed for this are L-tryptophan, vitamin B6 and magnesium. L-tryptophan is an essential amino acid – i.e. a substance that our body cannot produce, but must be supplied from outside. Unlike serotonin, this substance can cross the blood-brain barrier. The body also takes in B6 and magnesium with food. Serotonin is mostly produced in cells of the intestinal mucosa (approx. 90%), a smaller part directly in the nerve cells of the brain, as the blood-brain barrier is impassable for serotonin. Serotonin affects not only our sleep, but also our circulatory system, gastrointestinal complex and nerves. While low serotonin levels lead to aggressiveness and increased impulsivity, normal levels are associated with serenity, calmness and contentment.

… and in the gut our microbiome plays an essential role in good sleep.

The gut-brain axis…

The cells of the intestinal mucosa as well as the bacteria, viruses and fungi contained in the microbiome influence each other and thus have a considerable influence on immune cells, neurotransmitters and signalling substances that have an effect on our brain, which in turn has an effect on the microbiome. Not only our immune defence is influenced by this, but also our sleep or our mental performance, which in turn is improved or worsened by sleep.

…has an influence on the biorhythm, …

An altered or disturbed microbiome can influence the suprachiasmatic nucleus and thus our biorhythm. Obviously, with a healthy diet, the inhabitants of our microbiome are oriented towards a normal 24h-cycle, whereas an unhealthy diet promotes microbes that are not committed to this rhythm, leading to obesity (see here).

…mainly due to the diversity of microbes in our intestines.

Studies also show that above all a high diversity of the intestinal environment and a high number of lactic acid and bifidobacteria contribute to a good night’s sleep and high mental performance. The anti-inflammatory influence of lactic acid bacteria in particular benefits our immune system and thus our overall well-being. It is therefore alarming when entire species of microbes are lost from our microbiome.

Amazonian peoples, for example, live with twice as many intestinal bacteria as the average American. This is especially true of flexible microbes, which in traditional hunter-gatherer peoples like the Hadza lead to different microbiome compositions depending on the season, adapted to the seasonal diet. And it is particularly regrettable that this low diversity in our microbiome, which is caused by an unhealthy diet, is hereditary and after a maximum of four generations can no longer be saved by a change in diet (see here).

Why do we have to sleep so much at all? There’s room for improvement!

Maybe we divide and shorten our sleep…

In the course of self-optimisation, there are a number of so-called biohackers (if you don’t know what that is, here’s a super column) who also divide sleep into several sections for more efficient use of time and manage with much fewer hours in total.

Now, bi-phasic sleep – the division of the 8h sleep into two parts: a night part and a midday siesta – is known from more southern regions.

Polyphasic sleep, on the other hand – practised by Tim Ferris, for example – divides sleep into a more or less long main sleep phase (from 1.5-4.5h) and 2-5 20-minute short (REM) sleep phases. The participants describe an enormously increased performance during this time despite a difficult acclimatisation. In defence of this sleep optimisation, it is argued that the nightly 8h contains large parts of biologically unhelpful light sleep in addition to deep and REM sleep, and that polyphasic optimisation merely removes these parts from the sleep pattern without any loss in performance to be expected. In addition, it is assumed that monophasic sleep is an invention of modern times, since two nocturnal sleep phases with a waking phase in between are known from the Middle Ages and the Renaissance. Based on this, a polyphasic sleep pattern is also assumed for our ancestors.

…just like our ancestors?

However, a recent study of sleep among three hunter-gatherer peoples, the Hadza, the San and the Tsimane, conducted by Professor Jerome Siegel in 2015 with the help of portable sleep meters, revealed that these peoples firstly have only six and a half hours of night sleep, secondly do not take a midday nap and thirdly do not wake up at night. None of the groups knows a word for insomnia. These peoples wake up about 1 hour before sunrise, but do not go to bed at sunset but about three and a half hours after. The sleeping time was not based on the sunlight, but on the falling temperatures. The temperature also seems to be the reason why the San are the only group to wake up one and a half hours after sunrise in December.

No, rather not.

This study, as well as a look at our biological clock, suggests that a biphasic sleep pattern makes sense in hot countries, while the numerous short sleep phases in optimised polyphasic sleep deeply interfere with the biological processes of the organs and hormonal cycles. In the meantime, sleep research has also discovered that light sleep is also necessary for processing what has been learned. Doing without it must therefore also lead to losses in long-term performance. Therefore, I cannot imagine any long-term positive effect of these sleep patterns.

What does not help against sleep disorders – sleeping pills.

We have almost 2 million drug addicts in Germany because of the above-mentioned sleep disorders. The majority of them take benzodiazepines, which have an extremely high addiction potential. More than two thirds of the addicts are women and about one third are over 70 years old. The latter often leads to misdiagnosis of dementia or Alzheimer’s disease because of the similarity of symptoms. Since the effect of benzodiazepines only lasts a few weeks, patients often increase the dose on their own or combine it with alcohol. In addition, the substance accumulates in the body. If you take 20 mg a day, you will have a level of 150 mg in your blood after two weeks. This accumulation leads to habituation effects in the body and also causes the urgent desire to increase the dose.


Hopefully I have been able to show you how much you should think about your own sleeping behaviour, given the fundamental effects that lack of sleep or poor sleep quality has on your well-being. If you would now like to get some concrete tips on how to improve your sleep, just have a look here.

Yours, Claudia