What happens in sleep?

We spend approximately one-third of our lives asleep. This alone shows that sleep plays a central role in our lives. And for good reason: Sleep has many functions that are essential for a healthy everyday life. Here you'll learn exactly what happens during sleep and how you can get the most out of it.

Table of contents

1. Active while sleeping
2. Sleep phases at a glance
3. This happens during sleep
4. Sleep – the central recovery period
5. Conclusion

1. Active during sleep

Sleep = doing nothing? Wrong! Numerous essential processes take place during sleep, as it is the central regeneration period for our body and especially for our brain. It was long assumed that our brain is less active during sleep – in fact, it is just active in a different way. During the day, it continuously processes information, and these processes require a lot of energy. Although the brain only takes up about 2% of our body volume, it consumes about 20% of our total energy. When we relax and close our eyes, the activity of our nerve cells (neurons) slows down, and energy consumption slowly decreases.

During the night we go through several sleep cycles, which in turn are divided into different Sleep phases A cycle lasts approximately 90 to 110 minutes and occurs several times per night. The first two sleep cycles are particularly important for brain recovery. Therefore, they are also referred to as core sleep.

2. Sleep phases at a glance

After a short period of falling asleep, we typically enter a light sleep stage. This is when our muscles relax, our heart rate and breathing become more regular, and our body temperature drops.

This shallow sleep, in which we spend almost half of our sleep time, is followed by deep sleep. It dominates the first third of the night and causes our body to wind down even further, slowing our heart rate and breathing, and lowering our blood pressure. Especially during deep sleep, when neural activity is significantly reduced, our brain's energy stores can recharge. At the same time, numerous hormones and neurotransmitters are released that control and support metabolic and regeneration processes.

Following deep sleep, we then enter the dream sleep phase, also known as REM phases, in which our brain processes and evaluates the day's experiences. REM stands for "rapid eye movement," because during these sleep periods we dream and move our eyes rapidly back and forth under closed eyelids. For this to work, blood flow to the brain increases, blood pressure rises, and our heart rate and breathing become more irregular.

Core sleep, the first two sleep cycles, are particularly important for our regeneration. But what actually happens in our bodies while we sleep?

3. This happens during sleep

Learning and memory processes

At work, at school, or during leisure time – our brain absorbs information everywhere, both consciously and unconsciously. While we sleep, these impressions are stored, processed, organized, or deleted by the brain, and transferred from short-term memory to long-term memory. This way, relevant information is stored for the long term and made ready for retrieval, while unimportant information is deleted, so that after sleeping, we are ready to recollect the next day. Sleep therefore plays a central role in our ability to learn. You can learn more about learning while sleeping in this Article.

Strengthening the immune system

During sleep, the number of natural defense cells in the body increases and our immune system works at full speed to protect us from viruses, bacteria, and other pathogens. "The immune system is directly linked to the length and quality of our sleep," says sleep researcher and smartsleepfounder Dr. Markus Dworak. Getting enough sleep reduces the likelihood of getting sick and gives the body time to strengthen its immune system.

Cell renewal

Our hormone balance is also active while we sleep. Important growth hormones are released, which are involved in almost all functions in our body. They control enzyme production and cell renewal, help build and repair tissue, and support the regeneration of our body cells. Sleep is particularly essential for maintaining healthy skin, hair, nails, and connective tissue, and thus forms an important basis for a healthy and beautiful appearance. You can find out exactly how sleep makes us beautiful. here read more.

Optimization of metabolism

At night, the body has the rest it needs for important metabolic and digestive processes. Metabolic byproducts such as uric acid are broken down more efficiently, and fat metabolism is also active to provide energy for regeneration.

4. Sleep – the central recovery period

Sleep is essential for our body and mind in many ways. While our consciousness rests at night, our brain is by no means inactive – it processes, sorts, and stores the information and impressions of the day. Our body also needs sleep to repair body cells, regulate hormone levels and metabolism, and strengthen the immune system. These are numerous functions that are fundamental to our health and show us how important healthy sleep habits and sufficient sleep truly are.

5. Conclusion

• At night we go through several sleep cycles, which are divided into falling asleep, light sleep, deep sleep and dream or REM sleep phases

• During sleep, learning and memory processes take place that process, organize and store information and impressions of the day

• During sleep, growth hormones are released, which support cell renewal and regeneration and thus promote healthy skin, hair and nails

• Metabolism is regulated and optimized during sleep

• At night, the number of defense cells increases, which strengthens the immune system during sleep