Updated at: 15-04-2022 - By: Jane

Good health requires adequate sleep. Sleep is as essential to our survival as food and water. Since we spend nearly a third of our lives sleeping, it’s understandable.

During sleep, a variety of physiological activities take place:

  • Toxic waste and fresh information are stored in the brain.
  • The healthy functioning of the brain is supported by the communication and reorganization of nerve cells.
  • The body repairs cells, restores energy, and releases molecules like hormones and proteins.

The body repairs cells, restores energy, and releases molecules like hormones and proteins.

Cells are repaired, energy is restored, and chemicals such as hormones and proteins are released by the body.

Why do we sleep?

There’s still a lot we don’t know about why we sleep. Many people believe that there are multiple reasons why we need to sleep. Biologically, it’s probably essential.

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Sleep has been shown to benefit the body in a variety of ways by scientists. Following are some of the more popular hypotheses and explanations.

Energy conservation

To keep our bodies running at their best, we require sleep, according to the energy conservation hypothesis. We can lessen our caloric requirements by sleeping because our metabolism slows down when we’re asleep.

The fact that our metabolic rate drops while we sleep lends credence to this idea. Humans have been shown in studies to save 35% more energy per day when sleeping 8 hours a night than when awake the entire day.

The energy conservation theory of sleep claims that sleep is primarily designed to conserve energy during times of the day and night when it is more difficult and inconvenient to forage for food.

Cellular restoration

According to the restorative notion, sleep is essential for the body’s self-restoration.

Basically, sleep is supposed to allow cells to repair and regenerate themselves. It’s backed up by a slew of key sleep mechanisms, including:

  • repair of muscles
  • cellular production of proteins
  • development of cells in the body
  • release of hormones

Brain function

To function at its best, the brain relies on sleep. Reorganization of your neurons and other nerve cells is facilitated by this method.

Waste from the brain’s glymphatic system (waste clearing) is flushed out during sleep. It flushes the brain of toxins that accumulate over the day. A good night’s sleep allows you to wake up feeling refreshed.

A growing body of evidence suggests that sleep improves memory by eliminating or forgetting unnecessary information that might otherwise clog the nervous system and turning short-term memories into long-term ones.

Brain function is influenced by various factors, including sleep quality and quantity.

  • learning
  • memory
  • a capacity for creative problem-solving
  • creativity
  • making a choice
  • focus
  • concentration

Emotional well-being

Emotional well-being also necessitates adequate sleep. Brain activity increases during sleep in areas that control emotions, allowing for good brain function and emotional stability..

The following areas of the brain are more active when you sleep:

  • amygdala
  • striatum
  • hippocampus
  • insula
  • cortex of the prefrontal lobes

Amygdala is an example of how sleep regulates emotions. The temporal lobe of the brain, which is responsible for the fear response, is located here. When confronted with a perceived threat, such as a stressful circumstance, it’s what regulates your behavior.

An adaptable amygdala can be activated when you receive enough sleep. The amygdala, on the other hand, is more inclined to overreact if you’re sleep deprived.

Sleep and mental health are linked, according to studies. It’s true that insomniacs are more susceptible to mental health problems, but it’s also true that those with mental health problems are more likely to experience sleep problems.

Weight maintenance

Sleep affects your weight by controlling hunger hormones. In addition to ghrelin, these hormones include leptin, which promotes the sensation of fullness after eating.

Sleep affects your weight by controlling hunger hormones. In addition to ghrelin, these hormones include leptin, which promotes the sensation of fullness after eating.

Sleep affects your weight by modulating hunger hormones. These hormones include ghrelin, which stimulates hunger, and leptin, which enhances the feeling of satiety following a meal.

Through the regulation of hunger hormones, sleep has an impact on your weight. When it comes to weight loss, these hormones include ghrelin and leptin.

  • obesity
  • diabetes mellitus with hypertension
  • diabetic type 2

Proper insulin function

You can utilize insulin to help your cells convert glucose (sugar) into energy. Your cells, on the other hand, do not respond to insulin correctly in insulin resistance. Type 2 diabetes can develop as a result of chronically elevated blood glucose levels.

UHS Sleep

Insulin resistance may be protected by sleep. It maintains the health of your cells, allowing them to efficiently absorb glucose.

During sleep, the brain utilizes less glucose, which aids the body in maintaining a healthy level of blood glucose.


Sleep is essential to maintaining a healthy immune system. Sleep deprivation has been shown to weaken the body’s immune system, making it more vulnerable to infection.

It’s during sleep that your body produces cytokines, which are anti-infective and anti-inflammatory proteins. Antibodies and immune cells are also produced. They work as a team to keep people healthy by eradicating pathogenic microorganisms.

To put it another way, while you’re unwell or anxious, sleep is essential. Immune cells and proteins are needed in greater abundance during these times.

Heart health

Scientists believe that sleep improves cardiovascular health, even though the particular mechanism is unknown. This is due to the connection between sleep deprivation and cardiovascular disease.

The Centers for Disease Control and Prevention (CDC) recommends that adults get at least seven hours of sleep each night. Regularly receiving less than that amount can lead to a variety of health issues, many of which are detrimental to your heart’s health.

Heart disease risk factors, including the following, have been linked to insufficient sleep:

  • a high pulse rate
  • greater sensitivity of the sympathetic nervous system
  • an increase in inflammation
  • increased levels of cortisol
  • the accumulation of fat
  • insulin insufficiency

How Does Sleep Change During the Night?

As you sleep, you go through four to five stages of sleep. There are four distinct stages to a sleep cycle.

Rapid eye movement (REM) and non-rapid eye movement (NREM) sleep are subcategories of the four stages of sleep. The distinction between REM and non-REM stages of sleep necessitates the usage of these classifications.

Non-REM activity occurs in the first three stages of sleep. Stage 1 is the transition from nodding off to sleep, and it’s the shortest stage. As you go off to sleep, your body and mind slow down to Stage 2. During the first two stages, it’s simplest to be awakened.

As the body enters Stage 3, also referred to as profound sleep, it slows down even further. Meanwhile, brain activity slows and takes on a distinctive pattern of pulses, which may serve as a safeguard against unwelcome awakenings.

REM sleep is the final stage of sleep. Brain activity increases during REM periods to the same level as when you are awake, which is why the most powerful dreams occur during REM. The majority of our muscles are immobilized when we sleep in the REM stage, which prevents us from acting out our vivid dreams.

Between 70 and 120 minutes are required for each sleep cycle. Non-REM sleep is more prevalent in the first half of the night’s sleep cycles. Most REM sleep occurs in the latter half of the night. Sleep architecture refers to the succession of sleep stages and cycles throughout a single sleep period.

What happens when you sleep?

There are four stages of sleep that your body goes through. This cycle repeats several times throughout the night, lasting anywhere from 70 to 120 minutes at a time. During the course of a 7- to 9-hour sleep cycle, the stages repeat four or five times.

Non-REM (non-rapid eye movement) sleep and REM (rapid eye movement) sleep are the two main types of sleep in this pattern. There are four stages of sleep: three non-REM stages and one REM period.

Non-REM sleep is characterized by no eye movements, whereas REM sleep, which occurs during dreaming, is marked by fast eye movements.

The following is a chart outlining the various stages of sleep.

Stage 1: Non-REM sleep

Stage 1 occurs as soon as you’ve fallen asleep for the first time. Your brain waves, heart rate, and eye movements slow down when your body enters light slumber.

This part of the process lasts for roughly seven minutes.

Stage 2: Non-REM sleep

This stage represents the transition between light sleep and profound sleep.

Eye movements stop; the heart rate and muscles relax; and your body temperature drops. After a brief spike, your brain waves begin to calm down.

Time spent in stage 2 sleep is the longest throughout the typical night’s rest.

Stage 3: Non-REM sleep

During phases 3 and 4 of sleep, a state of profound slumber is established. Your muscles and eyes become immobile, and your brain waves slow even further as a result of this state.

The healing powers of a good night’s sleep cannot be overstated. Each day, your body works to restore and repair itself. You need this phase in order to wake up the next day feeling awake and energized.

Stage 4: REM sleep

About 90 minutes after you’ve fallen asleep, this period begins. During REM sleep, your eyes move rapidly from side to side.

Your brain waves and eye movements increase during REM sleep. Your respiration and heart rate pick up as well.

REM sleep is a common time for dreams to occur. Learning and memory are aided by this period in your brain’s processing of new information.

What Happens to Your Brain and Body During Sleep?

During sleep, virtually every component of the body undergoes significant changes. Many neurons in the brain are activated while we fall asleep, sending out messages to the rest of the body.

Research shows that sleep strengthens the cardiovascular and immunological systems and regulates metabolism, despite the fact that its biological purpose is still a mystery. During sleep, the body undergoes significant transformations that can be observed.


During non-REM sleep, breathing slows, with the lowest rates of respiration occurring in stage three of deep sleep. During REM sleep, breathing might become more rapid and even erratic.

Heart Rate

Stage 1 is when the heart rate begins to slow, and Stage 3 is when it slows the most. On the other hand, while a person is in REM sleep, the heart beats at the same rate as when they are awake.

Muscle Tone

The body’s total energy expenditure decreases as muscles relax during non-REM sleep. Atonia occurs during the REM state, when most muscles are paralyzed. As a result, there will be no jerking of the limbs in response to the content of the dream. However, the respiratory and ocular muscles remain active, and the darting of the eyes beneath closed eyelids is what gives rapid eye movement sleep its name.

Brain Activity

Measurements of brain waves in the course of sleep reveal distinct patterns that correspond to the various stages of the sleep cycle. A gradual decrease in brain activity occurs in Stage 1 of non-REM sleep, although there are several brief bursts of activity in Stage 2 and Stage 3.

During REM sleep, the brain’s activity increases significantly, resulting in a distinct set of brain waves. Because of this increased activity in the brain, REM sleep is often referred to be the stage of sleep during which people have the most vivid dreams.

Non-REM sleep, even with diminished brain activity, is also believed to serve a role in facilitating healthy brain function while awake, even if REM sleep is required for critical cognitive capacities, including memory consolidation.


Dreaming is most common and powerful during REM sleep, but it can occur at any time throughout sleep.. Non-REM dreams, on the other hand, tend to be more imaginative, immersive, or odd, whereas REM dreams tend to be more fanciful, immersive, or bizarre.

Hormone Level

Numerous hormones, such as the following, are controlled by sleep and the circadian rhythm, the body’s internal clock.

  • The sleep-inducing hormone melatonin
  • Ghrelin, a hormone that aids in bone and muscle growth and metabolism.
  • Cortisol, a stress hormone produced by the body.
  • Appetite-controlling hormones such as ghrelin and leptin

As we go through the stages of sleep, our hormone levels change, and the quality of our night’s sleep may have an impact on how much we produce during the day.

The impact of sleep on our mental health | SJ Versus Depression

How much sleep do you need?

The amount of sleep you need varies with your age. The CDC recommends the following lengths based on age, but this can vary from person to person.

  • 14 to 17 hours from the time of birth to the third month of life
  • 12 to 16 hours a day, including naps, for children aged 4 to 12
  • Between one and two years of age: 11 to 14 hours per day, including nap time.
  • 10-13 hours a day, including naps, for children ages 3 to 5.
  • 9 to 12 hours a day: 6 to 12 years old
  • Ages 13-18: 8 to 10 hours each day
  • Ages 18 to 60: 7 hours or more
  • 60-64 years old: 7 to 9 hours.
  • 7 to 8 hours for those 65 and older

What happens if you don’t get enough sleep?

Your body has a difficult time operating correctly if you don’t get enough sleep. Chronic health problems affecting the heart, kidneys, blood, brain, and mental well-being have been related to sleep deprivation.

Adults and children alike are at greater risk of damage if they don’t get enough sleep. For example, driving when fatigued has the potential to cause fatalities or significant injuries.

Older folks who don’t get enough sleep have a higher chance of falling and breaking bones.

Sleep deprivation can cause a variety of problems, including:

  • variations in mood
  • anxiety
  • depression
  • lack of recall
  • a lack of ability to concentrate
  • a lack of motor ability
  • fatigue
  • The immune system is impaired
  • the accumulation of fat
  • a high pulse rate
  • insulin insufficiency
  • like diabetes and heart disease, which are both long-term conditions
  • a greater likelihood of dying young

What Happens if You Have Insomnia?

As a result, insomniacs are unable to sleep for as long as they would like, resulting in a lack of total sleep. Thus, people may not be able to get enough sleep at night, resulting in daytime fatigue and bad impacts on their mood and thinking, as well.

Insomnia, which causes sleep loss, can upset the natural rhythms of the body’s sleep cycle. When people don’t get enough sleep, they may experience a rebound in REM sleep when they spend more time in REM sleep than they normally would. Too much brain activity can lead to irritability and increase mental health concerns like anxiety and sadness. This is not good for your mental health.

What Happens During Sleep if You Have a Sleep Disorder?

Sleep disorders can have a detrimental impact on your ability to get a good night’s rest. For example, frequent awakenings due to restless leg syndrome or sleep apnea might reduce restorative sleep by disrupting the regular sleep cycle. An irregular circadian rhythm may lead to a lack of rest or disrupted sleeping patterns.

What Happens When You Sleep Too Much?

Hypersomnia is a disorder in which one sleeps excessively. People with hypersomnia may find it difficult to stay awake during the day because of their severe daytime sleepiness. Some research shows a link between hypersomnia and altered patterns of restorative deep sleep and rapid eye movement (NREM) sleep, which may have an impact on how well a person rests as a whole.

Tips for Better Sleep

Better sleep can be achieved by adhering to good sleeping habits.16:

  • Make an effort to go to bed and wake up at the same times each night and day.
  • Begin a nighttime ritual that will help you unwind before you go to sleep
  • If you can’t sleep, limit the amount of time you spend in bed.
  • Keep the bedroom cool, dark, and quiet.
  • Don’t drink alcohol, smoke, or engage in excessive exercise in the evenings
  • Before going to bed, avoid using electronic gadgets with bright screens.

If you’re experiencing trouble sleeping, see a doctor. People who are trained in diagnosing and treating sleep disorders may recommend additional lifestyle adjustments or send you for an in-home sleep study.

The bottom line

Our health and well-being depend on a good night’s sleep. Your body and mind may regenerate, rejuvenate, and reenergize as a result of this.

Poor memory and concentration, reduced immunity, and mood swings are all possible side effects of not getting enough sleep.

A typical night’s sleep for an adult is between seven and nine hours. Consult your physician or a sleep specialist if you are experiencing difficulty sleeping. They can get to the bottom of the problem and help you get a better night’s rest.
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