Body processes

Deep Sleep Stages – Function, Task & Diseases

Deep sleep phases

During deep sleep , some of our body cells are highly active. During this time, the body processes a particularly large number of proteins in order to repair damage to the cells and form new ones. Deep sleep phases that are permanently too short or completely absent deprive the body of the opportunity to regenerate and open doors to metabolic diseases , premature aging processes and disorders of the body’s own defenses, including autoimmune disorders and cancer .

What are deep sleep phases?

Humans have five stages of sleep , of which stages 3 and 4 belong to deep sleep. We don’t dream at this time. In phases 1 and 2 we fall asleep or the sleep is superficial. The five sleep phases are repeated up to 6 times in the same order: phase 1, 2, 3, then in reverse 4, 3, 2, and finally REM. This happens over the 7-8 hours that a healthy sleeper needs.

A complete cycle is always around one and a half hours long. Immediately after the 20-30 minute sleep phase, the first deep sleep begins, which at 30-60 minutes is considered the longest and most regeneration-intensive phase. Towards morning, the last deep sleep lasts only a few minutes. REM sleep phases, on the other hand, are longest in the morning hours. Each deep sleep phase is followed by such a REM dream phase.

function & task

Sleep takes up a third of a human life. If this sleep is missing, we quickly recognize consequences such as exhaustion , irritability and lack of concentration . 

In deep sleep, the body repairs most of the important cell structures and organs. The body ‘s defenses produce important immune substances. Physically active people and people with a fast metabolism usually have longer deep sleep phases, which are not for nothing popularly considered the fountain of youth, like the well-known beauty sleep. This has its justification also in the medical sense.

Vital bodily functions such as muscle tension and breathing , heartbeat , blood pressure or body temperature get confused if there is no deep sleep or if it is too short. The hormones and the metabolism need the natural rhythm of mindfulness and sleep, of rest and activity.

Blood pressure, digestion and muscle tension decrease when we sleep. Blood pressure and body temperature drop, especially during deep sleep. Growth hormones are released , which stimulate cell repair and stimulate and strengthen the immune system.

At the same time, what has been learned and impressions from the short -term memory are copied into the cerebral cortex , the temporary storage is emptied again, so to speak, and made ready for new experiences. During the rest periods, relevant items are sorted and reactivated.

In the morning – imperceptibly and naturally for us – the entire body system is strengthened. Deep sleep thus promotes our well-being, improves our ability to concentrate and learn , and strengthens our immune system.

Deep sleep is a short vacation for body and soul . The muscles relax, blood pressure and circulation are reduced, the stress hormone cortisol is at its lowest compared to other sleep phases.

In phase 5, the REM dream sleep, the muscle tone is then maximally relaxed, the eyes flutter and roll and people dream. Falling asleep and light sleep phases are short, lasting only 10, 20 or 30 minutes.

Diseases & Ailments

Lack of sleep increases the level of the stress hormone cortisol in the blood . If the person has a permanent lack of sleep or very irregular sleep duration or even falling asleep, this can already have a negative effect on the body’s defenses, because too much cortisol at night means permanent stress . This damages the adrenal cortex and thus directly affects the metabolism. 

Next, insulin secretion and glucose metabolism , which regulate the body’s ability to handle glucose , can be affected . In short phases of raising children and the interrupted night’s sleep due to illness, you can already feel these effects, which regenerate again as soon as the critical phase is over. However, if the condition persists, health problems creep in.

Persistent lack of sleep can be linked to weight gain and an increased risk of developing diabetes . The overall turnover decreases, the glucose metabolism can be permanently disturbed, which results in an unbridled appetite, especially on high-calorie food. The vicious circle begins. Even after a week of shifts with less than six hours of uninterrupted sleep per night, more than 700 genes are damaged per night.

Lack of deep sleep is a risk factor for obesity and many metabolic disorders . Harmonious bodily processes to maintain an energy balance are sensitively disturbed. The natural sense of appetite or hunger, the balance of energy intake and energy expenditure, quickly fall into the ranges of type 2 diabetes mellitus with sleep deprivation .

People who are deprived of sleep for a very long time have hallucinations , personality disorders or depression up to suicidal thoughts.

With age, on the other hand, the deep sleep phases naturally decrease. This is not a cause for concern, as for older people, naps in between are a wonderful respite and activity levels off somewhat overall. As a result, less sleep is required at night. However, if you want to be active and alive into old age with maximum health, you would do well to take loving care of yourself and your healthy deep sleep phases.

Lack of deep sleep can have the following effects:

A healthy deep sleep is the basis for health, quality of life and coping with modern life with all its stimuli and stresses.

Lisa Newlon
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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.