Published on 11 November 2021

What Is Deep Sleep?: Things You Should Know

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Have you ever had the feeling wherein you just slept and woke up all blank? Without any dream and dozed off, that is what we call deep sleep. So, what are you? Snorlax from Pokémon? Or Kumbh Karan from Raavan? Anyways, to know more, let's scrutinize deep sleep in deep.

Let's Know About Nap.

Waking up all muzzy and not being able to think accurately is what happens when you are in a deep sleep. So, what exactly is it? Deep sleep is also called slow-wave-sleep, wherein one's body automatically slows down while in sleep, which in turn contrasts to REM, that is rapid eye moment sleep, and thus, to know more about this, let's understand these terminologies precisely.

Types Of Sleep.

There are a lot of things that happen when we are in a sound sleep or dreaming about Hawaii. Thus, let's know what exactly goes on when we are in the process. But before that, let's get familiar with REM and NREM.(Goodenough, D.R., Lewis, H.B., Shapiro, A., Jaret, L. and Sleser, I., 1965)

  1. REM- REM, rapid eye movement sleep is a zizz wherein one's eyes scurry in various directions but do not convey any information to the brain. This sleep usually occurs after about 90mins of sleeping, which leads to dreams. According to the study, about 50% of babies and 20% of adults indulge in REM. This sleep is more like a drowse which is polar to that of NREM. Thus, let us know about NREM.
  2. NREM- NREM is nonrapid eye movement sleep wherein one doze off blank without any eye movement. This usually occurs in three stages, and the last two stages are considered as NREM, where it gets toilsome to wake up. This slumber does not lead to any vivid dreams as the body slows down.

Now that we are aware of REM and NREM let's look at the stages of sleep.

Stages Of Sleep.

There are about four stages of sleep wherein one goes through the cycle of REM and NREM, which starts through:

Stage 1. Sleeping But Still Awake. (NREM SLEEP)

This is the stage that lingers between sleeping and being awake; people are usually well aware of what is going on in the surroundings, wherein you shut your eyes but are still sharp and about to fall into a deep sleep. During this phase, your body reacts as follows-

  1. Your body starts to slow down, which leads to slower movements.
  2. Heart rate slows down along with eye movements and breathing.
  3. The body and muscles relax, but one may experience sudden jerks or even the body falling, which is common in this stage.
  4. This lasts for about 10-15 mins.

Thus, now that you are half asleep, let's see what happens when we fall asleep.

STAGE 2 The Process Of Deep Sleep. (NREM SLEEP)

This is the process where you are about to go into a deep sleep or more like the preparation period where your body goes through certain changes, namely:

  1. This is the stage where one's muscle tones as well as relaxes.
  2. The temperature of the body drops, and the heart rate, as well as breathing, becomes normal.
  3. Eye movements stop, and the brain slows down; however, one may also experience sleep spindles where in the brain my burst with rapid activity.
  4. This sleep usually lasts for about 90 mins to 120 mins.

Hence, this is what happens in stage two; now that we are about to go into a deep sleep, let's know what happens in stage three before we go zzz.

STAGE 3: Deep Sleep. (NREM SLEEP)

This is the phase where one doesn't know what is going on and is into blank sleep and thus is also called delta sleep, wherein the slow brain waves occur. During this process, the body tends to go through the following procedure:

  1. Muscles relax completely
  2. No eye movements
  3. The brain sends slow delta waves, wherein the brain slows down.
  4. The mind goes pitch black without which might not lead to any vivid dreams.

Thus, this is what happens when in a deep sleep. It usually gets challenging to wake up from this sleep; however, NREM thus shifts to the fourth stage that is REM. 

STAGE 4: Awakeness. (REM SLEEP)

This is the stage wherein your brain kick starts its activity and might thus lead to light sleep. As previously mentioned, this stage usually occurs for about 90 mins. Therefore, let's see what goes on in this sleep:

  1. Breathing becomes faster and is irregular
  2. Muscles are still relaxed and in the state of coma or no movement
  3. Eyes lead to REM, that is, rapid eye movement
  4. Vivid dreams may appear
  5. Brains start up the activity.

Thus, this is what goes around when you reach the fourth stage and lead to the phase of awareness.

Hence, the stages are as follows stage 1 NREM, stage 2 NREM, stage 3 NREM, STAGE 4 REM, and stage 5 awareness.

Therefore, these are the stages of sleep, but why is it important? To know more, let's dive right into it.

Why Is Deep Sleep Important?

Deep sleep is important is an aspect that keeps us refreshed when we wake up and re-energizes our body, which gives us strength to do activities and mental stability. Thus, let's know more about it in depth. 

During The Stages Of Sleep.

Deep sleep is vital as it not only refreshes our body but also gives us strength and energy to perform the activities. But how does this happen? When our bodies are in stages, there are a lot of activities that our body goes through. Such as

  • Rebuilding and regeneration of new cells- this is the process where new cells are formed, and damaged cells are repaired that increases the efficiency of the body functioning.
  • Secretion of hormones for bone and muscle growth- hormones are secreted that lead to the development and aid the tissues that regenerate the cells that maintain the blood flow and do not let our body catch any illness.
  • Boosting the immunity system that combats any illness- Enough 7-9 hours of sleep leads to a better immunity system as the above-mentioned process takes place with leads the body to grow and develop and thus, fights all the ill ailments in the body and shields our body that leads to a healthy body.
  • Replenishes and improves the memory game- as sleep gives the brain time to rest and recover, it leads to boosting the memory power and improves the thinking capacity, thus keeps us focused.

Thus, these are the few reasons why sleep is essential. Now that we are well-versed with what happens in the rest, let's come to an end.(Meisner, D. and Wenisch, T.F., 2012)


As it is very well quoted by Thomas Dekker, an American actor saying, "sleep is like the golden chain that binds our health and body together" thus, as sleep is also called beauty sleep, it stands by its name as it, therefore, makes our bodies healthy and beautiful.