Why do we dream, the cosmos in the head

Questioner: Hermann F. from Esslingen

Some hunt criminals or fight shaggy monsters, others eat house-high chocolate cakes or meet their secret crush. Everything is possible in a dream. But why does the brain produce so many colorful films every night??

The editor’s answer is:

Michael Schredl, sleep researcher at the Central Institute for Mental Health in Mannheim: There are no people who do not dream. Even if we don’t remember, we still dreamed. Dreaming is defined as our subjective experience during sleep. This subjective experience never turns off – just as when awake. If you repeatedly wake people up to sleep or during sleep, they almost always report scraps of dreams.

Whether dreaming one own Has a function, but is difficult to answer. Because in order for me to know what someone dreamed, he has to tell me the dream. It may be that he thinks about the dream and therefore has a better idea when he is awake or can cope better with a situation. Then I don’t know whether the effect comes from the dream itself or from telling and thinking about the dream.

Nevertheless, there are several theories about the meaning of dreaming: during sleep, our brain solidifies and processes what we have learned during the day. Some scientists suspect that dreaming plays an important role in this. Their idea is that when dreaming, the brain mixes new information with old information and then stores it. Participants report that their dreams mix new and old experiences, both of which are often emotionally connected. The sleeper works on topics that concern him and may find solutions to his current problems through the creativity of dreams.

A similar theory says that in dreams we prepare for situations and train practical skills that we will need later. Because even small children experience a lot of REM sleep, the sleep with the most intense dreams. This stage of sleep occurs in four to five phases at night and accounted for approximately twenty percent of total sleep in an adult. REM stands for Rapid Eye Movement, because the eyes move quickly back and forth under the closed eyelids. During this time the brain is most active, compared to NON-REM sleep or deep sleep. Today it is assumed that we also dream in the other phases of sleep, but the pictorial intensive experience is most pronounced in REM sleep.

Other scientists assume that we learn in dream to deal with fearful situations. Nightmares are just the summit of the iceberg. Whenever you experience a tricky situation during the day, you solidify your knowledge in a dream to avoid this dangerous situation next time. Because those who avoid dangers have a higher chance of survival.

The whole brain works to create dream images, and there is a lot of resemblance to the waking state. If you want to move, the motor cortex is also active. Only the transmission to the muscle is blocked in the brain stem, otherwise the dreaming would move in his sleep. Especially in REM sleep, there are two differences regarding brain activity: The amygdala, which is responsible for processing emotions, is more active during dreaming than when awake. In contrast, the prefrontal cortex, which is primarily responsible for planning and straightforward thinking and acting, fires less strongly than when awake. Some researchers suspect that dreams are often bizarre due to the lower activity of the prefrontal cortex.

recorded by Hanna Drimalla

emotions

“Emotions” are neuroscientists who understand psychic processes that are triggered by external stimuli and which result in a willingness to act. Emotions arise in the limbic system, an ancient part of the brain in terms of tribal history. The psychologist Paul Ekman has defined six cross-cultural basic emotions that are reflected in characteristic facial expressions: joy, anger, fear, surprise, grief and disgust.

eye

Eyeball / Bulbus oculi / eye bulb

The eye is the sense organ for the perception of light stimuli – of electromagnetic radiation of a certain frequency range. The light visible to humans is in the range between 380 and 780 nanometers.

sleep stages

When we sleep, we go through several cycles of four consecutive sleep phases within one night. The activity of the brain waves initially decreases successively until their (main) frequency in stage N3 – deep sleep – is only 0.5 to 2 Hertz. The first three sleep phases (N1, N2, N3) can also be summarized as non-REM sleep. The fourth phase is called REMsleep designated. This is characterized by rapid eye movements, low-amplitude brain activity at mixed frequencies and reduced muscle tone. A non-REM / REM sleep cycle lasts about 90 minutes, with deep sleep dominating the start of sleep, while REM sleep takes up an increasing part of this time from cycle to cycle.

Primary motor cortex

Primary motor cortex / – / primary motor cortex

An area of the frontal lobe in the front wall of the central furrow. It is considered a higher-level control unit, responsible for arbitrary – and fine motor skills. This is where the cell bodies of the central motor neurons sit, whose axons move to the basal ganglia, to numerous core areas in the brain stem and to the spinal cord. The Betz giant cells only occur in the primary motor cortex, particularly large motor neurons, whose axons move directly to the motor neurons in the anterior horn of the spinal cord without prior synaptic switching.

brainstem

The "stem" of the brain, on which all other brain structures are "hung", so to speak. It comprises – from bottom to top – the medulla oblongata, the pons and the mesencephalon. It goes down into the spinal cord.

emotions

Cortex

Cerebral cortex / cortex cerebri / cerebral cortex

The cortex cerebri, or cortex for short, denotes the outermost layer of the cerebrum. It is 2.5 mm to 5 mm thick and rich in nerve cells. The cerebral cortex is strongly folded, comparable to a handkerchief in a cup. So arise numerous turns (gyri), crevices (fissurae) and furrows (sulci). When unfolded, the surface of the cortex is approximately 1,800 cm 2 .