How to improve the quality of sleep and how it affects health

Sleep is one of the most important parts of our life, and without good sleep, the body cannot recover enough. This is especially important for athletes because training tires the body and the muscles need time to regenerate.

Why are we sleeping?

For the proper functioning of the human body, you need to get a sufficient amount of nutrients and fluids, and it is important to remember sufficient and high-quality sleep. We spend about a third of our lives in a dream, and giving up sleep will first lead the body to a psychotic state, and then even to death. Randy Gardner set a record for how long a person did not sleep. Randy did not sleep for 11 days and 24 minutes in 1965. At the last stage of the experiment, he had fragmented thinking, his speech was incoherent, and he could solve simple mathematical tasks for more than a few minutes. Sleep is extremely necessary for a person for many reasons, and its lack leads to a decrease in vital functions and death. 

Scientists are aware of the processes that occur during sleep, as well as the benefits of quality sleep. However, the very reason that a person falls into a strange state of hibernation in which dreams appear is not yet known. Also, not only people but also all animals need sleep for their existence.

What happens to us while we sleep?

Sleep phases

The whole process of sleep is not only about closing your eyes, falling asleep, and waking up again. During sleep, the human brain goes through cycles that have several phases, and different processes occur. One such cycle lasts approximately 90 minutes, and approximately 4-6 cycles are repeated over a 7-9 hour sleep period.


Three phases of NREM and one phase of REM alternate during one cycle.

  • NREM phase (no rapid eye movement) – also known as non-REM or the slow sleep phase, is part of the cycle before the REM phase. NREM is divided into 3 phases, which differ in the depth of sleep. During the NREM phase, the eyes do not move;
  • REM (rapid eye movement) – the deepest phase of sleep – accounts for approximately 25% of the total amount of sleep and is the deepest phase of sleep. The body is completely paralyzed during the REM phase, only the eyeballs move. In this phase of sleep, information is transferred from short-term to long-term memory. 

The NSF (National Sleep Foundation) classifies the sleep cycle into the following phases:

1. N1 non-REM (once level 1) is the slowest part of the cycle, lasts about 7 minutes, and makes up about 2-5% of the sleep cycle, during N1 the pulse, eye movement, and cardiac activity slow down. It is considered a transitional state between sleep and wakefulness;

2. N2 non-REM (once level 2) – the phase between slow and deep sleep, this is the longest part of the cycle, which is about 45-60%. There is a decrease in temperature and pulse, muscle relaxation;

3. N3 non-REM (previously 3 and 4 levels) – also called “delta sleep”. This is the beginning of deep sleep when the rhythm of the brain waves decreases even more, and at this stage, the eyes and muscles do not move. At this stage, approximately 40% of sleep occurs, during which cells, tissues, and muscles are restored, and the body replenishes energy reserves;

4. REM – this is 20-25% of sleep, during which brain activity, heart rate, and respiration are activated. The REM phase begins approximately 90 minutes after we fall asleep, the brain processes the information, and during the REM phase, we also have dreams.

The Importance of Sleep for Health

During sleep, many processes occur in the body that affects human health. There are the most important reasons for good sleep quality:

Best athletic performance

Have you ever wondered how long athletes usually sleep? According to the NSF (National Sleep Foundation), 7–9 hours of sleep is ideal sleep time for adults, but it would be better for athletes to sleep even longer. Having enough sleep will improve your athletic performance in several ways. You will feel an increase in training intensity, speed, energy, coordination, and at the same time, mental abilities will also improve.

Quality sleep helps maintain stable blood sugar

The glucose level in the body depends not only on the choice of diet and physical activity but also on sleep. Glucose levels fall during the deep phase of sleep, but when you sleep little, your body doesn’t rest at all. Without sleep, the body may react worse to sugar levels in the body and cell needs. A 1999 study examined the effects of sleep reduction on young men. Reducing sleep to 4 hours a day for 6 nights led to the onset of symptoms of the initial stage of diabetes. However, the symptoms disappeared after a week of recovered and prolonged sleep. Several studies indicate a connection between sleep deprivation and type 2 diabetes. This means that too short sleep can not only reduce productivity but also lead to serious illness.

Weight changes

The reason for weight gain may be lack of exercise, poor nutrition, and poor sleep. According to scientific articles, “certain” levels of hormones in the brain affect this. Chronic lack of sleep leads to an increase in the level of ghrelin (a hormone that stimulates appetite) and a low level of leptin (a hormone that suppresses appetite).

Emotional problems

Lack of sleep is also associated with changes in the emotional state. A sleepy person is irritable, and one who gets enough sleep feels much better. Nevertheless, this is not only about a feeling of happiness, since lack of sleep not only destroys your emotional balance but also affects the ability to evaluate the feelings of others. With a lack of sleep, problems may arise with the recognition of human expressions and emotions. Not only physical activity is reduced, but also the ability to communicate with other people. Prolonged sleep problems can lead to emotional disturbances. It is proven scientifically that 90% of people with depression also have a lack of sleep.


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