How long sleep do we need? What is REM, non-REM and why do we need to dream?

How long sleep do we need? What is REM, non-REM and why do we need to dream?
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It is true that we should sleep long enough to feel refreshed and full of energy when we wake up in the morning. But how long is that?

How much sleep is necessary for us?

Length versus quality. Which is more important?

And here, somewhere between those two variables, is the answer.

It could be summed up like this.

The quality of your sleep is never a substitute for its length. But it is also a rule that if the sleep is of any quality but too short to regenerate the body, it is also not enough.

Does sleep serve to regenerate the body?

Of course it does. But it must be divided into mental and physical. And each requires a certain amount of time.

But let's get this out of the way.


What is it?

Basically, it's a state. Specifically, an altered state of consciousness. It's largely influenced by hormones.

The most prominent of which is melatonin.

What is melatonin?

It's a hormone produced mainly in the brain, in the pineal gland. Its production is influenced by the intensity of light. If we're supposed to sleep, it has to be dark for melatonin to be released. It makes us sleepy enough to fall asleep.

That's how it works.

But melatonin doesn't determine how much sleep is needed.

Melatonin is made 10 times more at night than during the day.

Let's get back to sleep.

As we mentioned, it's a state of consciousness that ensures the body's regeneration. That is, it's a regularly recurring rest. However, its lack causes health complications.

This regularity, quality and duration are disrupted by sleep disorders:

Read more in this article:
More about sleep disorders.
What length of sleep is needed?
Sleep and its research.

Sleep disorders

Let's take a closer look at what happens in sleep disorders.

Insomnia is actually insomnia. A person has trouble falling asleep. When they do, they wake up frequently. Sleep is shallow and the sufferer doesn't get enough rest.

Here, however, a distinction must be made between insomnia as such and difficulty falling asleep, for example, after severe physical exertion or emotional strain.

Insomnia itself is a chronic disorder. Such individuals often sleep for only 2 to 3 hours. Very often they wake up early in the morning and then do not sleep again.

In this article you will read more about insomnia and its causes.

Hypersomnia, on the other hand, is excessive sleepiness.

The problem, however, is that such conditions occur in the sufferer during the day. Then, at a time when he or she should or must be active, a state of sleep suddenly comes on.

Actually, it manifests itself in uncontrollable seizures. One cannot resist them at all. These states last for a few minutes, but they also come during physical activity or during conversation with another person.

This makes it a very dangerous condition.

Of course, it is not to be confused with the state after a wakeful or sleepless night.

Narcolepsy itself is a subset of hypersomnia. It's increased sleepiness with hallucinations.

The symptoms are basically the same as those of hypersomnia, because it belongs to this group. The sleepiness that comes on at any time of the day cannot be suppressed at all by will.

Often, and very quickly, the dreamy phase of sleep occurs. At a time when the sufferer is still aware of his surroundings. For this reason, narcoleptics often perceive these dreams as reality.

They're called hypnagogic hallucinations. But they're not hallucinations as such. They're dreams that are very realistic. Visual, auditory, even tactile.

Narcoleptics don't have to fall into complete sleep. They're only in a state of extreme drowsiness. But short or incomplete sleep means they're on the borderline between sleep and wakefulness for days and nights.

Therefore, they do not rest at all and suffer from fatigue.

Somnambulism, otherwise known as sleepwalking or lunaticism, is a sleep disorder that manifests as a type of unconscious behavior.

The moon, however, has no influence on this state, despite popular belief.

Experts believe it's a waking disorder, a state of incomplete awakening.

In a certain phase of sleep, the so-called non-REM (we will talk more about it), the muscles are not disabled. Unconscious behaviour starts their activity. The motor and autonomic system is activated without reaching the waking state. Thus, the motor activity of the person is not controlled by the will.

Such an individual is therefore moving, but at the same time asleep.

With increasing age, the state of sleepwalking decreases. Scientists believe that this is because the stages of sleep also shorten.

Bruxism is the grinding of teeth. The sufferer doesn't know it. Unless it occurs at night.

Alcohol and caffeine, which affect the central nervous system, can also have a major effect on the sleeping phases.

How much sleep is needed?

Some of the findings and facts are really interesting.

Why do we need to sleep?

According to experience, it is clear that health and feeling good during the day depends on a healthy night's sleep.

What happens to the body when we fall asleep? Everybody knows it, but let's take a look:

  • Often the eyes start to burn
  • the pupils constrict and the eyelids become heavy
  • heart rate drops
  • reactions slow down
  • reduced production of body fluids (saliva, gastric juices, urine)
  • breathing slows down and less oxygen is consumed

But what happens next?

When we're suddenly almost unaware of anything.

The discovery of the encephalograph (EEG) in the 1920s also helped sleep research.

An encephalograph (EEG) is a device that records the electrical activity of brain cells. It does this by using electrodes that are placed on the head of the person being studied.

And so this encephalograph (EEG) was used by a certain Professor Nathaniel Kleitman of the University of Chicago for sleep research. This was back in the 1950s. Since then, a lot of time has passed and a lot of other research has taken place.

But his findings provide a basis for understanding what happens to us during sleep.

Sleep and its research

Let's explore sleep in more detail.

When we are in a relaxed state with our eyes closed, but still awake, the brain sends out 8 to 12 oscillations per second. These oscillations are regular. They are called the alpha rhythm.

In light sleep, these waves slow down and increase.

During deep sleep, the EEG records only 1 to 3 oscillations per second.

So what did Mr. Kleitman find?

His research showed that humans reach four different depths of sleep.

But the stage of deep sleep from which we slowly awaken in the morning isn't reached just once in one night.

Within a 7 to 8 hour sleep, the stages of falling into sleep are repeated 4 times and emerging from it 5 times.

And this is the fundamental key to understanding how long sleep is needed for our bodies.

When a person falls asleep, the first stage lasts about 5 minutes. The second and third stages pass very quickly and the person is in the fourth stage. This is the deep sleep stage, which lasts at least half an hour.

After this time, the person returns to shallower sleep, that is, to the first stage.

It takes some time to fall back into deeper sleep. However, in the second stage of sleep, the deep stage is no longer reached. If it is, it is not as long as in the first stage.

Then it is repeated through the third and second stages into the first.

After about twenty minutes, the deeper sleep comes again and the transition through all the stages to the fourth.

The whole cycle of falling into sleep and vice versa continues throughout the night. Each part lasts approximately 90 minutes.

The closer it gets to morning, the longer the first stage of shallow sleep lasts. The third to first stage is thus progressively shorter.

Before waking in the morning, a person is usually only in the first and second stages of sleep.

But the American professor also came across another fact that was astonishing at the time.

In addition to discovering the cyclical nature of sleep, it turned out that its different stages were associated with certain eye movements.

When we fall asleep, the alpha rhythm fades and the eyes move slowly until they stop. We often dream bizarre things then, from which a spasmodic blink can snap us out of it.

When we fall asleep and the brain slips into the first stage of sleep, the EEG records short and irregular waveforms. We can still be woken up by an unexpected sound, for example. People often claim they weren't asleep at all.

If nothing disturbs us, we slowly enter the second stage. Then the eyes move slowly under closed lids.

In the third stage of sleep, blood pressure and body temperature drop. Heart rate slows. We breathe slowly and deeply.

We don't perceive our surroundings and move into stage four.

About 90 minutes after falling asleep, we move through stage three into stage two. That is, light sleep.

This is where a change occurred that surprised scientists at the time.

As their subjects moved from stage two to stage one, their eyes began to move rapidly and jerkily.

REM stage and non-REM stage

They called this stage REM. The term comes from the English term "rapid eye movement", meaning rapid eye movement. The eyes then move synchronously from side to side, as if they were watching a tennis match.

In addition, during this phase, the EEG records that the brain is very active. Blood pressure rises, breathing is irregular and oxygen consumption is increased. Men often develop erections.

To scientists at the time, everything pointed to the experience of strong emotions by people who are exposed to them in the REM phase of sleep.

To make matters worse, in this stage, a man is completely detached from the world and even harder to arouse than in deep sleep.

Sleepers move restlessly immediately before and after the REM stage. However, during the REM stage, even though their blood pressure is elevated and their brain is active, they do not move at all. The eyes move rapidly, but the muscles are flaccid.

And so the researchers continued their research.

They found that it's during the REM phase that people dream. But after a long study of sleeping people, they found that we dream during the non-REM phase too. Although before, scientists thought the exact opposite.

The non-REM phase is the phase of slow eye movements. The name is derived from the English term "non rapid eye movement".

The REM phase of sleep is repeated up to 5 times during a single sleep period.

It would take 5 years to make a film consisting of all the REM dreams of one person.

More than 10,000 people took part in the research. Whenever they were awakened from the REM phase, 80% of them claimed to have just dreamt something. But only 7% claimed the same when they were awakened during the non-REM phase.

That's why the researchers thought only the REM phase was dreamy.

Everything changed when the experimental subjects awakened from the non-REM phase were asked if they were thinking about anything.

Suddenly, up to 75% answered in the affirmative. They were indeed dreaming, that is, more or less thinking, although not as visually or emotionally as in the REM phase.

So we dream almost all the time, both during the REM phase and the non-REM phase. It's just the nature of the dreams that's different.

People who were awakened at any stage of sleep claimed to have dreams. But when they could sleep through the night without waking, they said they didn't dream at all.

Why must we dream and sleep?

We all dream. Even those who say they don't dream dream dream.

Hence the question: Why do we have to dream and sleep?

Are sleep and dreams biologically necessary for us, or can we exist without them?

And last but not least, which is more important, sleep or dream?

There are many examples of how not allowing sleep is devastating to the body. Sleep deprivation has been used as an effective method of torture since ancient times. Not allowing it is dangerous.

There have been many experiments on dreams and sleep. One in 1959 in New York's Times Square.

The main actor was a local disc jockey, Peter Tripp, whose main aim was to find out what effects sleep deprivation would have on his body. The event was also a charity event.

Peter Tripp lasted 201 hours and 13 minutes without sleep.

At the start of the experiment, he was barely able to stand from fatigue. After two days, he saw cobwebs on his shoes while changing. But that was only the beginning. It continued with bugs crawling on the tablecloth, which were in reality stains. He saw a white rabbit hopping around. It continued with memory problems.

After a hundred hours without sleep, his ability to concentrate was diminished. Even minimal exertion was an insurmountable problem. He had trouble with the alphabet.

After a hundred and ten hours, he began to suffer symptoms of delirium. States of nonsensical laughter alternated with insult. He suffered such hallucinations that he saw the doctor present dressed in crawling worms.

He became convinced that the agreed upon two hundred hours without sleep had long since ended.

After about one hundred and twenty hours, he opened a drawer, from which he said flames burst out. He ran out into the street, claiming that the fire had been set by scientists to see how he reacted.

After a hundred and fifty hours, he lost his sense of direction. He didn't even know who he was. He examined the wall clock, which had turned into the plastered face of an actor. He began to doubt his identity and wondered if he was the actor.

He finally succumbed to the belief that he was the victim of a conspiracy of scientists.

It should be added here that it is better not to try such experiments at all.

After 200 hours, he was subjected to more than an hour of examination. Only then was he finally able to sleep. The scientists thought he would sleep so deeply that he would miss the REM stage of sleep.

In the end, he slept for 13 hours and 13 minutes.

But the important thing was the discovery that he hadn't slept as deeply as he'd thought. But his sleep was rich in dreams.

Of his 13 hours of sleep, he spent 3 hours and 46 minutes in REM. That's 28% REM dreams.

Normally, REM dreams take up about 20% of an eight-hour sleep period.

So Tripp clearly had a strong need to catch up on his dreaming. Although it's likely that his hallucinations during the eight days he was awake were in the nature of dreams. His body was probably using them as a substitute.

The fact that we dream all night is certain. There's no way to separate dreams from sleep.

But the question is whether sleep or dreaming is more important to us.

Experiments have been carried out to prevent people from dreaming. Before they could develop REM sleep, they were awakened.

Two important facts emerged. All the subjects compensated for the loss of sleep. They had REM phase dreams. After five days, they had to be awakened from them up to 30 times in one night.

The second fact was that on uninterrupted nights without waking, REM phases accounted for up to 40% of their sleep. They were clearly catching up.

It's not for nothing that they say you can't sleep before you sleep, you can only sleep after you sleep.

Experimental subjects awakened during REM phases exhibited a variety of disorders:

  • Inability to concentrate
  • exhaustion
  • increased hypersensitivity
  • memory lapses
  • weaker muscle coordination

Another group woke up during the non-REM stages, the second, third and fourth stages. Simply deep sleep.

The result?

These people were perfectly fine. They didn't show any behavioral disturbances.

For the researchers, the implication was that it wasn't sleep deprivation that was causing the unwanted symptoms, but dreaming.

Sleeping for more than 8 to 8.5 hours is worse for a person's health than sleeping for about 5 hours.

Of course, we are talking about a good night's sleep. There are more answers to why we need to sleep, and especially to dream.

Read also the article.

The benefits of sleep and dreaming

It is scientifically proven that during the third and fourth stage of sleep, the non-REM stage, growth hormone is secreted. It maintains the growth of our body and is required for the synthesis, or merging, of proteins.

Most of the sleep of young people is in the non-REM stages. It's obvious why.

In the REM stages of sleep, brain protein is formed. It supports the development of brain cells and keeps them working.

Sleep helps process and store new information. It acts as a kind of programming for our brains.

Getting a good night's sleep after heavy studying makes sense.

So it's all related. The length of sleep with the depth and quality of it. When to go to sleep and when to get up?

The questions are many and we are gradually finding the answers.

What is important is the so-called sleep hygiene.

Sleep should last at least 7.5 hours, no more than 8.5. Of course, if nothing wakes us up during that time, it is a big plus. It is best to get used to going to bed at the same time if possible. It is good if it is before midnight.

Too much sleep disrupts the circadian system in the brain. Simply the biorhythm.

You can sleep till noon. But it doesn't do you any good if your cells are already on their cycle at 7:00 a.m.

The biorhythm is tricked, but the person is sleepy and tired.

Here are the rules of sleep hygiene and the consequences of sleep deprivation

Rules of sleep hygiene Consequences of sleep deprivation
  • Regular sleep habits - going to bed and getting up at the same time
  • the bed should only be used for sleeping
  • eliminate alcohol, caffeine and nicotine before bedtime
  • an easily digestible dinner
  • regular physical activity during the day
  • a calming atmosphere in the bedroom
  • a sleep ritual
  • relaxation exercises before sleep
  • inability to concentrate
  • exhaustion
  • increased hypersensitivity
  • memory lapses
  • weaker muscle coordination

From all the information mentioned above, sleep has its own rules. It follows its own rhythm and needs, which should not be disturbed. We should observe and follow its needs.

So that we feel refreshed and full of energy in the morning.

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Interesting resources

  • - SLEEP DISORDERS FROM A NEUROLOGIST'S PERSPECTIVE, MUDr. Mária Tormašiová, PhD. Department of Neurology, UPJŠ Faculty of Medicine
  • - wakefulness and sleep
  • Von BUTTLAR, Johannes. Time jump. Bergisch Gladbach: Bastei-Verlag Gustav H. Lübbe GmbH, 1997. 174 p. ISBN 80-220-0931-8
  • - How Much Sleep Do I Need?
  • - How Much Sleep Do We Really Need?
  • - How many hours of sleep are enough for good health?
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