Sleep cycle: Which sleep is the most restful?
27. September 2020
326
Sleep is not just sleep: the human sleep cycle is made up of different sleep phases. An undisturbed cycle with the correct sequence of the individual sleep phases is essential for our well-being and health. Without a good night's sleep, we have little energy for the day ahead of us and are unable to perform to our full potential in everyday life. But which sleep phases exist and how do they make up a complete sleep cycle? We explain how human sleep is structured, how it changes with age and whether there is possibly a certain phase of our sleep that is particularly important for our recovery.
- How is a sleep cycle structured?
- The sleep cycle changes with age
- Especially important: The deep sleep phase
- Supporting a healthy sleep cycle
How is a sleep cycle structured?
Human sleep is divided into four to five sleep phases, which form one sleep cycle. The phase of falling asleep, in which our consciousness shifts from the waking state to sleep, is followed by a phase of light sleep. This is followed by a phase of deep sleep, in which regenerative processes take place in our body. Finally, we experience a phase of REM sleep, also known as dream sleep.
Within a healthy person’s sleep cycle, the phase of falling asleep is typically followed by several phases of light sleep and deep sleep, before the cycle is completed by a REM sleep phase. This cycle, which lasts about 90 minutes, is repeated four or five times before we wake up in the morning. If you look at the length of each sleep phase, you will notice that it varies with each new cycle. While light sleep increases in length with each new cycle, so that it makes up half of our sleep, the length of deep sleep decreases slightly. The time we spend in REM sleep also increases with each cycle. All in all, we get about 75 minutes of dream sleep per night.
The sleep cycle changes with age
If you compare the sleep duration of a baby with that of an adult, you will see that our age has a decisive effect on our sleep duration and thus also changes our sleep cycle. The 16 to 18 hours of sleep that babies need is far too much for us adults. Instead, on average we manage with seven to eight hours of sleep. The composition of our sleep is also different for us adults than for babies, who spend about half their sleep in the REM phase. For us adults, on the other hand, only 25 percent of our sleep is dream sleep. The main part of our sleep is light sleep.
Especially important: The deep sleep phase
Even though it is crucial for us humans to go through all sleep phases several times each night in order to feel well rested, one phase of our sleep cycle stands out in particular: the deep sleep phase is the most restful for us, both physically and mentally. This becomes even more obvious when we consider the physical processes that take place during deep sleep. As our body reduces muscle and brain activity to a minimum and also slows down our breathing and heart rate, we enjoy the deepest physical relaxation. Certain growth hormones are released, which strengthen our immune system and allow our cells to regenerate. Stress hormones such as cortisol, on the other hand, are at their lowest level.
Deep sleep is the phase of our sleep cycle in which we sleep particularly soundly, and it is therefore much more difficult to wake us up in this phase. Our brain is busy processing the experiences of the day. Newly acquired knowledge is also stored now. Therefore, it is particularly harmful for our health if our deep sleep is shortened due to sleep disorders.