Sleep and Its Power, or What Happens to the Body at Night and Why It Is So Important for Us

Article author: Karolína Weissová, Marketing specialist, WeCare
Date: July 6, 2026

Sleep is just as important for our body as a quality diet or regular movement. Yet we often take it for granted and underestimate its true impact on health, mental well-being and the body’s long-term regeneration. The moment we fall asleep, a number of biological processes start in the body that affect our energy, hormonal balance, immunity and ability to manage stress. It is during the night that cells are renewed, the nervous system regenerates and information is stored in memory. Quality night-time rest is therefore not just passive relaxation, but an essential part of long-term health, vitality and mental balance.

What are the phases of sleep? 

Our night-time rest is not one uniform whole, but consists of several cycles that repeat throughout the night. Each cycle lasts approximately ninety to one hundred and twenty minutes and alternates between two main forms of brain activity, known as the Non-REM phase and the REM phase.  

For easier understanding of how the body regenerates at night, imagine sleep as a pyramid made up of three levels:

• Sleep cycle: During the night, we go through approximately 4 to 6 cycles. One such cycle lasts 90 to 120 minutes. Two main sleep phases alternate within it, according to the level of brain activity.
• Sleep phases: Each individual cycle consists of two completely different phases – Non-REM (resting) and REM (active).
• Sleep stages: The Non-REM phase is further divided into 3 stages, from the lightest falling asleep to the deepest sleep.

The Non-REM phase makes up roughly 75–80 % of the night and is divided into 3 stages, from light drowsing through light sleep to the deepest sleep. In this phase, biological repair of muscles, bones and physical regeneration takes place. 

In contrast, the REM phase makes up the remaining 20–25 % of the night. It is a phase characterized by rapid eye movements and high brain activity. This phase takes care of our psyche, emotions and sorting of thoughts. 

For the overall renewal of the body, the entire REM phase and the deep sleep stage, which belongs under the Non-REM phase, are key. If any part of this cycle is disrupted, we immediately feel it in our energy, concentration and mood.

Deep sleep as the key to regeneration and longevity

This deepest stage of the Non-REM phase represents an absolutely essential moment for the body. It is at this time that blood pressure decreases, breathing slows down and muscles relax. The body begins to produce growth hormone, which stimulates cell renewal and healing.

“Deep sleep is the most important phase of the sleep cycle in terms of the body’s regeneration. It is during this phase that cells and tissues are renewed, important metabolic processes are regulated and mechanisms supporting brain health are activated. If deep sleep is insufficient or frequently interrupted, the body does not have enough space for full regeneration.

Deep sleep also supports the storage of information in long-term memory and activates the lymphatic system, which helps remove waste substances from the brain. A growing body of scientific knowledge suggests that long-term poor-quality sleep may contribute to an increased risk of neurodegenerative diseases, including Alzheimer’s disease. Quality deep sleep is therefore considered one of the key factors in brain health and healthy aging,” explains MUDr. Gertrúda Čápová

How to naturally support deep sleep?

Watch the timing of your last meal: Heavy meals force the digestive tract to work at full speed, which prevents the body from entering the deepest phases of rest.

Optimize the temperature: The human body needs to cool down slightly to transition into deep sleep. The ideal bedroom temperature is around 18 °C.

How REM sleep affects our mind

The abbreviation REM stands for rapid eye movements, which are typical of this phase. During it, brain activity paradoxically almost matches the waking state. This is when we have the most vivid dreams and the brain processes emotions, experiences and new information.

“REM sleep is essential for mental balance, working with emotions and the ability to concentrate. Its long-term deficiency often manifests as increased stress, irritability or mental fatigue,” adds MUDr. Gertrúda Čápová.

Normally, REM sleep should make up approximately twenty to twenty-five percent of the total sleep time. Without enough of this phase, we may have difficulties with concentration, learning and managing stressful situations.

How to naturally support the REM phase?

Sleep long enough: Since REM phases predominate only in the second half of the night and toward the morning, with shortened sleep (less than 6 hours) you deprive yourself of this important mental cleansing.

Reduce alcohol:. Alcohol may help you fall asleep, but it acts as a depressant that prevents the brain from entering the REM phase in the first half of the night. This disrupts the natural sleep cycle, and because of this disruption you then lose quality REM sleep during the rest of the night.

Sleep hygiene and its effect on sleep quality

The quality of our night-time rest is largely in our own hands. Properly set sleep hygiene plays a major role, meaning a set of habits that prepare the body and mind for a calm transition into sleep.

“It is regular evening routine and quality sleep hygiene that help the body naturally switch into rest mode and support deep sleep,” explains MUDr. Gertrúda Čápová.

The main pillars of how to improve sleep include:

• going to bed and waking up regularly at the same time
• limiting caffeine, alcohol and heavy meals before bedtime
• the right bedroom environment with enough darkness, quiet and suitable temperature
• limiting blue light from phones and televisions
• managing stress through meditation, breathing techniques or a warm bath

A conscious evening routine is a great signal for the body that it is almost time to rest. Try putting your phone away an hour before bedtime, taking a warm shower, opening your favorite book and treating yourself to a cup of WeCare herbal tea, which will pleasantly put you on a wave of relaxation. 

In addition to these lifestyle measures, targeted support for the body can also help support quality sleep. The product about your SLEEP contains effective extracts and amino acids that support the production of hormones responsible for easy falling asleep and the smooth progression of all sleep cycles.

What can long-term poor-quality sleep cause?

If we deny the body the rest it needs over the long term, it begins to take its toll. In the short term, irritability, fatigue, reduced immunity or microsleep while driving may appear. However, chronic sleep deficit poses a risk. Long-term poor-quality deep sleep may contribute to metabolic disorders, hormonal imbalance, weight gain and cardiovascular problems.

The good news, however, is that the human body has an enormous ability to regenerate. Once you start paying attention to your sleep regime, the negative effects can be reversed and your body will thank you with a surge of new energy.

Insomnia and the most common causes of sleep disorders

Insomnia is one of the most common sleep disorders today. It manifests as difficulty falling asleep, frequent waking during the night or poor-quality sleep that does not provide sufficient regeneration.

“Insomnia is not only a problem with falling asleep or waking during the night. If it persists for a longer period, it can significantly affect the regeneration of the body, hormonal settings, brain function and overall health. Quality sleep is one of the basic pillars of long-term vitality and healthy aging,” warns MUDr. Gertrúda Čápová.

The causes of insomnia often differ according to age and lifestyle. In young people, common reasons include stress, excessive use of technology or mental overload. At an older age, insomnia may appear in connection with hormonal changes, health complications or the use of certain medications.

If you struggle with insomnia, do not despair – often, small gradual steps are enough to regain control over your sleep. The key is not to push too hard. When you cannot fall asleep, do not stay in bed with negative thoughts. Instead, get up, do a calm activity for a while in dim light and return when natural fatigue comes. Quality sleep affects our energy, concentration, mental well-being and ability for long-term regeneration. It is the stage of deep sleep and the REM phase that play an essential role in the renewal of the body, working with emotions and the overall functioning of the body.

If they are disrupted over the long term, fatigue, higher stress levels, insomnia and weakened regeneration of the body may gradually appear. That is why quality sleep should not be the last priority of the day, but a natural part of everyday health care. A regular routine, proper sleep hygiene and an environment in which the body can truly regenerate all play a major role. Even small changes in everyday habits can significantly affect how well we sleep, regenerate and function throughout the entire day.