Man's dream

Main article: Human brain

Cleaning the brain during sleep

The cerebrospinal fluid in which the brain floats performs its cleaning and washing, being one of the most important links of the glymphatic system.

In other words, cerebrospinal fluid removes different debris from the brain, flushing it predominantly during sleep, through channels compressed and decompressed by glial cells.

Lymphocyte count depends on sleep quality

In the 2010s, it was found that the quality of sleep has a significant effect on the number of lymphocytes and their function. If a person chronically lacks sleep, his lymphocyte activity decreases. As a result, a person with insomnia or simply a short sleep duration provides himself with a high vulnerability to any kind of disease.

Two phases of sleep

In the brain, two phases of sleep are sequentially alternating. Each with its own features: slow (deep) and fast sleep.

Deep makes up about 80% of all sleep time. This phase is characterized by slow brain waves, muscle relaxation, calm deep breathing.

Also, during slow sleep, memories are consolidated: recent events are transferred to long-term storage. But not all in a row - less important memories over the past day are cleaned up. Connections between neurons (synapses) contract in size, which is why weak connections are "cut out" and these impressions are forgotten.

The remaining 20% is rapid sleep or rapid eye movement (BDH) phase. During it, we see dreams.

In the fast phase, the brain is very active, the muscles are paralyzed, the heart rate increases, breathing becomes uneven. Reduced REM sleep time has been linked to the risk of dementia.

Sleep paralysis during the BDH phase of sleep

Approximately 40% of people experience at some point in their lives carotid paralysis. They wake up but are unable to move.

This happens if you wake up during BD sleep when muscles are paralyzed.

In rare cases, people report seeing ghostly figures during sleepy paralysis.

One of the hypotheses connects this is a faulty phenomenon in the way our brains build a body model.

Being unable to sense a paralyzed body, the brain mistakenly searches for it in the wrong place and therefore creates hallucinations.

Dreams

They can last from a few seconds to an hour. They get longer as the night goes on, but are forgotten almost immediately.

Why does a person have dreams and what information do they carry? Unfortunately, for 2019, science still has no exact answer to the question.

It is believed that dreams are associated with learning and memory, because after new impressions we usually see more dreams.

At this time, researchers are inclined to believe that dreams are the result of a special circulation of excitation through neural connections in the brain, at the time of transition of short-term memory to long-term memory. It is the process of transforming one memory into another that gives rise to dreams, so most often we dream of the events of the past days or what we thought about quite recently.

Freud's take on the nature of dreams

Psychotherapist Sigmund Freud believed that sleep is primarily a reflection of a person's desires in his real life.

Freud was convinced that all those emotions and desires of a person come to life in a dream and appear in the form of unclear images and symbols. The simplest example: at the moment when a person is thirsty at night, before waking up, he will most likely have a dream about how he drinks water.

Freud believed that in order to solve a dream, it is enough to analyze your own attitude to life and try to connect all the events with the images that you have seen.

What Russians dream

Dream map: What region does people dream of? Compiled by search queries, 2021

Medical sleep

Main article: Anesthesia

But this is how immersion in medical sleep occurs.

Sleep Improvement Devices

Main article: Devices for improving sleep

Sleep diseases

Insomnia

Main article: Insomnia

OSA, obstructive sleep apnea syndrome

Main article: OSA - obstructive sleep apnea syndrome

Consequences of poor sleep

2023

How lack of sleep destroys the brain. Scientific explanation

On September 6, 2023, the American Chemical Society (ACS) released the results of a study suggesting that lack of sleep has a detrimental effect on the brain. Moreover, regular sleep deprivation can increase the risk of developing Alzheimer's disease and other neurological ailments.

It is noted that lack of sleep leads to neurological damage to the hippocampus - part of the limbic system of the brain, which is involved in the mechanisms of the formation of emotions and memory consolidation. To better understand the processes taking place during sleep deprivation, experts studied changes in the quantitative content of proteins and ribonucleic acid (RNA).

Lack of sleep has a devastating effect on the brain

In experiments in mice, the researchers extracted proteins from the rodent hippocampus and identified those whose numbers changed after two days of sleep deprivation. Sleep-deprived mice appeared to have decreased levels of pleiotropin (PTN). Further, using RNA analysis, experts determined the molecular path by which the loss of PTN leads to the death of hippocampal cells.

Gene co-expression analysis revealed a potential mechanism by which PTN provokes cognitive impairment caused by insomnia through the MAPK (mitogen-activated protein kinase) signaling pathway, the paper said.

The researchers also found that PTN has links to Alzheimer's disease and other neurodegenerative disorders in humans. Assessment of PTN levels can serve as an indicator of cognitive impairment resulting from insomnia. In general, the authors of the work say, healthy sleep protects the brain from degradation. At the same time, regular sleep deprivation provokes the death of neurons. The findings in the future could help develop new treatments for neurodegenerative ailments.^[1]

Cause 8% of all deaths attributed to poor sleep

At the end of February 2023, scientists at the American College of Cardiology published a study in which they reported that young people with healthy sleep habits gradually decrease the likelihood of premature death. Moreover, about 8% of deaths due to any cause may be in this respect associated precisely with poor sleep.

Good sleep can play an important role in supporting a patient's heart and overall health, a study has found. Scientists have noticed a clear dose-response relationship, that is, the more favorable factors a person has in terms of higher sleep quality, the greater the step-by-step reduction in all-cause mortality and cardiovascular mortality.

In young people with healthy sleep, the likelihood of premature death decreases over time

For their analysis, a team of scientists from the American College of Cardiology included data from 172,321 people (average age 50 years, 54% women) who participated in the National Health Survey between 2013 and 2018. This survey is conducted each year by the Centers for Disease Control and Prevention (CDC) and the National Center for Medical Statistics. For the purpose of assessing the health status of the US population and included questions about sleep and sleep-related habits. According to the scientists, this is the first study conducted on a nationally representative contingent that examined how multiple sleep behaviors, not just sleep duration, can affect life expectancy.

About two-thirds of the study participants described themselves as white, 14.5% as Hispanic, 12.6% as black and 5.5% as Asian. Because the researchers were able to link participants to National Mortality Index records (through December 31, 2019), they were able to examine the association between individual and combined sleep factors and all-cause and cause-specific mortality. Participants were followed for an average of 4.3 years, during which time 8,681 people died. Of these, 2,610 people (30%) died from cardiovascular disease, 2,052 (24%) from cancer and 4,019 (46%) from other causes.

The researchers assessed five different sleep quality factors that they derived from responses collected as part of the survey. Factors included:

1. Ideal sleep duration - seven to eight hours a day;
2. Difficulty falling asleep no more than twice a week;
3. Sleep problems no more than twice a week;
4. Avoiding sleeping pills; feeling rested after waking up at least five days a week.
5. Feeling good rest after waking up at least five days a week.

When conducting the analysis, the researchers considered other factors that may have raised the risk of death, including lower socioeconomic status, smoking and alcohol consumption, and other medical conditions. Compared to those with zero to one favorable sleep factor, those with all five were 30% less likely to die from any cause, 21% less likely to die from cardiovascular disease, 19% less likely to die from cancer, and 40% less likely to die from causes other than heart disease or cancer.

Among men and women who reported having all five measures of sleep quality, life expectancy was 4.7 years longer in men and 2.4 years longer in women compared to those who did not have one or only one of the five favorable low-risk sleep elements.

More research is needed to determine why men with all five low-risk sleep factors doubled life expectancy compared to women who had the same quality of sleep. One limitation of the study is that sleep habits were self-reported rather than objectively measured or tested. In addition, there was a lack of information about the types of sleep aids or medications used, and how often or long participants used them. Future research is needed to understand how this increase in life expectancy may continue with age, as well as to further examine the observed sex differences.^[2]

Chronicle

2024: The first recorded communication of people in sleep took place

On October 11, 2024, it became known that a startup from California REMspace, developing technologies to improve sleep and conscious dreams, for the first time in history allowed two sleeping people to exchange a message. The results of the work are said to be a major milestone in sleep research. In the future, the technology could find applications in a variety of fields, including psychiatry and training in certain skills. Read more here

2023: People in the world sleep less and less

People around the world are increasingly monitoring the quality of sleep using mobile gadgets. However, the duration of the night rest is reduced. This is stated in a large-scale study by Samsung, the results of which were released on October 26, 2023.

Analyzed data on approximately 716 million sleep sessions received from users of the Samsung Health app from around the world. This program is designed to track physical activity, count calories spent, monitor body composition and assess the general state of the body. It is said that in two years (by mid-2023) the number of users who track sleep at least once a week has grown by 182%. The collected indicators help to improve the quality of night rest, and therefore improve well-being.

Sleep duration, according to Samsung, from June 2021 to May 2022, averaged 7 hours and 3 minutes. However, in June 2022 - May 2023, this value decreased to 6 hours and 59 minutes, that is, it dropped below the required 7-hour threshold recommended by the National Sleep Foundation (NSF). It turned out that the highest sleep deficit is observed among young people: in 20-year-olds, sleep deprivation is almost twice as much as in 70-year-olds - 49 minutes versus 29 minutes, respectively.

Sleep quality directly affects human health. At the same time, it is not enough to simply lie down earlier and get up later. The state of rest at night is affected by daily routines, the NSF study found. Specific eating times, levels of physical activity and even lighting are of importance. The use of gadgets before going to bed leads to violations: light from the screens of phones, laptops and TVs negatively affects falling asleep. NSF experts recommend using special relaxation methods to get better sleep.^[3]

2018: Asia-Pacific countries average sleep duration

2018 data

Notes