The importance of sleep phases

Our sleep is made up of several sleep cycles in which we go through different sleep phases night after night. Find out here what sleep phases there are and what importance the individual sleep stages have for a restful night.

Table of contents

  1. How does our sleep work?
  2. The sleep phases at a glance
  3. The importance of sleep cycles
  4. Conclusion

1. How does our sleep work?

Our sleep is essential for our energy balance and numerous important recovery, repair and building processes in our brain, tissue and cells. Sufficient, restful sleep is therefore one of the most important foundations for healthy body function and an efficient, healthy everyday life. Experts generally recommend that adults sleep 7 - 8 hours per night - and that's not a coincidence. Every night our sleep is made up of different sleep cycles, which in turn consist of different sleep stages: the falling asleep phase, the light sleep phase, two deep sleep phases and REM sleep. In order to feel rested in the morning, it is very important to go through enough sleep cycles and give the body time to regenerate. We give you an overview of the different sleep stages and explain what importance the individual phases have for a restful sleep.

2. The sleep phases at a glance


Die Schlafphasen und Schlafzyklus

Sleep phase

The sleep phase refers to the last minutes before “real” sleep. In this phase, the body switches off, relaxes and comes to rest. For adults, falling asleep takes around 5-20 minutes.

    Light sleep phase

    During this period of sleep, our muscles relax, pulse and breathing become more even and the body temperature drops. We spend almost half of our sleep time in this rather superficial sleep, in which we are still quite susceptible to external stimuli such as noise or light. On average, we reach the light sleep phase about 15 minutes after falling asleep.

    Deep sleep phase

    Das Tiefschlafstadium

    The light sleep stage is then followed by deep sleep. It dominates the first third of the night and ensures that our body shuts down even further, heart rate and breathing slow down and blood pressure drops. In this stage, known as “slow wave sleep,” the frequency of brain waves drops and nerve activity is significantly reduced. Now the energy stores in our brain are recharged and numerous hormones and messenger substances are released that control essential metabolic and regeneration processes. Deep sleep is therefore the central recovery period for our body, in which proteins, cells and tissue are repaired, detoxified and built up, the immune system is trained and energy reserves are renewed. And our brain is also active, as declarative memory, which is responsible for learning facts and memories, is formed in deep sleep.

      REM sleep phase

      After deep sleep, we slide into the dream sleep phases, also known as REM phases. REM stands for “Rapid Eye Movement”, because during these sleep periods our brain processes and evaluates the experiences of the day and we move our eyes quickly back and forth under our closed eyelids. For this to work, blood flow to the brain increases, blood pressure rises and our heart rate and breathing also become more irregular. At the same time, we are in what is known as sleep paralysis, in which the brain stem blocks the transmission of commands to our muscles to protect us from uncontrolled movements and injuries during vivid dreaming. During REM sleep, important processing and learning processes take place in the brain and procedural memory, which forms the basis for subconscious skills such as automated movement sequences and motor learning, is formed.

      3. The importance of sleep cycles

      Schlafphasen/Wachphasen im Überblick

      During the night we go through several sleep cycles. One cycle lasts approx. 90 to 110 minutes and consists of the fixed sequence of the five sleep stages, with the ratio of sleep phases within a sleep cycle changing over the course of the night. At the beginning of our sleep we experience longer periods of deep sleep because these are urgently needed to restore the energy reserves used up throughout the day. At the end of the night we spend more time in REM sleep, in which the available energy can be used for important brain functions. The first two sleep cycles, the so-called core sleep, are particularly important for the recovery of the body and brain and the most important restorative processes take place in our cells and the nervous system. In order to wake up completely restful in the morning, it is important to go through around 4 to 7 sleep cycles and therefore sleep between 7 and 8 hours.

      Find out more?

      In our new podcast sleep SMART! we talk to Dr. Markus Dworak about the sleep phases and learn more interesting and scientific information from him about how important our sleep cycles and the different sleep stages are for a restful night and a healthy day! Listen now ➨

      4. Conclusion

      • Sleep consists of several sleep cycles that vary throughout the night and are divided into five sleep stages
      • The five sleep stages are: falling asleep phase, light sleep phase, deep sleep phase, REM sleep phase
      • During deep sleep, energy reserves are filled and the most important regeneration and building processes take place
      • A restful sleep consists of 4 - 7 sleep cycles and therefore lasts at best between 7 and 8 hours per night.

      Greetings and see you soon!

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