Body processes

Stages of Sleep – Function, Task & Diseases

sleep stages

Sleep is an important aspect of everyone’s life. Adults sleep about 6 to 8 hours a day. The episode can be divided into several sleep phases . Restful sleep can play an important role in general health.

What are sleep stages?

There are two basic types of sleep: REM sleep and no-REM sleep. No-REM sleep, in turn, can be divided into further phases.

During a night, there are usually four cycles of the sleep phases. The more time is spent asleep, the longer the REM episodes become. At the same time, these represent the time when people become involved in most dreams.

Thus, sleep is a change of different phases. Dream phases are followed by deep sleep , which in turn can be briefly interrupted. In total, an episode lasts about 90 minutes. On average, people wake up 28 times. However, if the interruption lasts less than 3 minutes, the next morning’s apparition will not be recorded in memory.

Certain medical devices make it possible to monitor sleep and control what phase the person is in. Such examinations are carried out in a sleep laboratory using an EEG . The EEG measures the brain waves and records a completely differentiated image of nerve activity in the waking state. Some complaints and illnesses make a stay in the sleep laboratory unavoidable.

function & task

Sleep is used for recovery of the organism. The task spectrum of nocturnal rest has not yet been fully researched. What is certain, however, is that the brain does not rest during sleep. Instead, it is busy processing the impressions, experiences and adventures collected during the day. 

In some people, this process is partially expressed in the dreamed. The brain differentiates between important and unimportant information. While storing the relevant ones, it removes the irrelevant trains of thought. Such processing is not possible during the day.

In order to avoid hallucinations , the brain must be isolated from all stimuli, as is the case at night. In the sleep phases, newly learned things are also processed and anchored in the brain, which has a positive effect on the learning effect.

Other functions of sleep include strengthening the immune system , regulating the metabolism , releasing growth hormones and restoring the psyche .

The deep sleep phases are particularly important for a relaxed feeling the next morning. First, however, there is the falling asleep phase . A change in brain waves can be observed here. These are longer and slower.

However, the falling asleep phase represents the transition, so sleepers can easily wake up in this episode. The perception of sensory impressions is reduced and the body is already beginning to relax. There is a general stabilization of heart rate and breathing, the muscles lose tension.

The first stage of the no-REM phase sometimes takes only a few minutes. The relaxation of the muscles can lead to muscle spasms, which is often perceived as a feeling of falling.

In the second stage of the no-REM phase, deeper sleep gradually begins. While the eyes rarely move, the activity of the brain increases. In this phase fewer dreams occur. If they do make themselves felt, a reference can often be made to a real event.

Stage 3 continues the second phase of the no-REM episode and concludes with the deep sleep phase. This is where the active regeneration of various structures of the organism takes place. The body is in a state of maximum relaxation. The activities of the brain and eyes are reduced to a low level, breathing and heart move regularly. In the deep sleep phase, waking up a sleeping person is the most difficult.

Diseases & Ailments

The majority of Germans have already become acquainted with complaints when falling asleep or sleeping through the night. There are different types of sleep disorders . Overall, however, they express themselves through a poor quality of nocturnal rest. Those affected often feel tired, drained and powerless. The ability to concentrate is limited, while irritability often increases. 

The sleep rhythm can be disturbed due to various reasons. These include, for example, shift work, depression and other difficult decisions that put a strain on the psyche .

Most people with insomnia suffer from insomnia (insomnia). On the one hand, there are difficulties falling asleep, on the other hand, sleep is often interrupted by phases in which the person concerned is awake. Thus, there is a lack of sleep at the end of the night. Other patients, on the other hand, find sleep early, but spend it very restlessly and wake up early in the morning.

Insomnia is often triggered by lifestyle habits. Excessive consumption of coffee and alcohol, cigarettes, certain medications, but also chronic pain, cardiovascular problems , hormonal factors, headaches and thyroid disorders are suspected here.

People who snore, on the other hand, often do not notice that their sleep has been interrupted. Breathing pauses occur, which can result in sleep apnea , which is dangerous to health . This not only reduces the sleep quality of the snorer, but also that of any fellow human beings.

Restless legs, on the other hand, prevent you from reaching the sleep phase due to a movement disorder. Those affected suffer from tingling, which is often perceived as unpleasant. In most cases, the symptoms are only alleviated as soon as you get out of bed and start moving. In this way, sleep can be interrupted several times in one night.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.