Deep Sleep vs REM Sleep – A Fight For The Title Belt, Who Wins?

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In the red corner we have “Deep”.

In the Blue corner we have “REM”.

And in the battle of Deep Sleep vs REM Sleep who wins?

You decide…

The sleep cycles we go through during the night have always fascinated me. I invariably felt that with a proper understanding I could enjoy the perfect night’s sleep.

It didn’t actually turn out to be as easy as that, but by studying the sleep cycles I managed to appreciate why I generally woke up feeling groggy and tired (I also realized what I needed to do to stop this from happening again and again).

REM sleep is probably the best known sleep cycle, but there are in fact another four (some may argue there are only another 3 sleep cycles).

In this article I want to look at why each sleep cycle is important to us, but my focus will be on deep sleep and REM sleep.

Cycling Through The 5 Stages of Sleep

We sleep in cycles and as I’ve mentioned the best known is REM, or rapid eye movement, sleep.

Not surprisingly rapid eye movement sleep is instantly recognizable, as the eyes of the sleeper start to dart around.

Many researchers and scientists tend to break down our sleep cycles into 2 broader categories, non-REM sleep and REM sleep.

Non-REM sleep is then further broken down in 4 stages (although most scientists cite three and put stage 3 and 4 together and count it as one sleep cycle). 

Light Sleep

This is when your body is just winding down. Your muscle activity typically slows down, although the muscles may be prone to the occasional twitch, And your breathing and heart rate start to prepare you for the deeper sleep that is to come.

The first stage of light sleep is nothing more than the transition from being awake to asleep and then this typically makes up approximately 3% of your sleep cycles.

You actually only go through the first stage of light sleep once through the entire night (unless you wake up during the night of course) and this is replaced by REM sleep in subsequent sleep cycles.

Stage 2 of Light Sleep

The second stage of light sleep is when everything starts to slow down – your breathing pattern and heart rate slows, your eye movements dwindle right down, your brain wave activity reduces, and there is also a slight decrease in body temperature.

You are literally shutting off for the night.

However, even though brain wave activity reduces there is the occasional surge of activity, which is the brain consolidating and transferring information from your short-term memory to your long-term memory.

This is also why it is often suggested that you study before you go to sleep or even listen to revision notes as you drop off. You are more likely to retain this information at a higher rate than at any other time of the day.

You also spend more time in this second stage of sleep than any other, in fact over 50% of your nightly sleep is spent in this stage.

Deep Sleep

Deep sleep and REM sleep are often confused with each other, but they are actually extremely different.

Deep sleep is when the body secretes certain growth hormones which are essential for repairing and rebuilding the body’s cells.

This stage is also when your brain waves are at their slowest.

The 2nd Stage of Deep Sleep (Very Deep Sleep)

As I’ve said above, the two stages of deep sleep are often lumped together as one stage.

Just to show the difference, you typically spend on average 6% of the night in the first stage of deep sleep and 15% in the second.

This is the stage of sleep when it is the most difficult to wake you up, and often if for any reason you are woken during this period of sleep you will feel extremely lethargic and irritable.

As long as you get enough deep sleep during the night you will always awake feeling alert and refreshed. However, if you don’t get enough deep sleep you will feel very tired and fatigued.

This is the reason why you often feel exhausted the following day even though you “slept” throughout the night for a good 8 hours – unfortunately, you didn’t get enough deep sleep.

REM Sleep

I’ve mentioned that REM sleep is probably the most famous of all the sleep cycles and you will typically experience this approximately an hour and a half after falling asleep.

REM sleep is most commonly associated with dreaming and can be identified by the rapid movement of the eyes, hence the name.

You will also process memories and emotions during REM sleep and your brain goes into even deeper recovery.

Your breathing is typically rapid and shallow, your muscles relax, your heart rate, brain waves and blood pressure increase to levels more reminiscent of wakefulness than of being asleep.

In fact, this is why dreaming occurs during REM sleep, as many of the body’s functions are so close to wakefulness.

Interestingly, there are a couple of chemicals in the brain which literally paralyze the arms and legs during REM sleep, so you’re unable to physically act out what you are dreaming about.

Could you imagine if this wasn’t the case?

Well I’d constantly be falling off cliff edges, running away from the baddies, or drop-kicking my partner in the face.

Deep Sleep – The Good, The Bad & The Ugly

So, as you can see there are various benefits to different stages of sleep, but as we are looking at deep sleep vs REM sleep, it’s only right that I look at these stages in a little more detail.

We now know that short-term and long-term memory, and overall learning is supported during sleep and this also occurs through glucose metabolism in the brain during deep sleep.

The pituitary gland also secretes hormones, including human growth hormone during deep sleep, which is especially important for the development and growth of the body.

The other main benefits of deep sleep include:

  • Restores energy
  • Regenerates the cells
  • It increases the blood supply to the muscles
  • It helps to strengthen your immune system
  • And it promotes both the growth and repair of your bones and tissues

Deep sleep will help the brain to process any information that you come across during the day and without enough deep sleep this information cannot be converted to your memory.

It also happens to be the stage of sleep which is associated with various disorders like bed wetting, sleep eating, sleepwalking, and night terrors.

There are certain conditions linked to not getting enough deep sleep such as, heart disease, stroke, diabetes, and Alzheimer’s disease.

There isn’t actually a specific amount of deep sleep you should be getting on a nightly basis, but the younger you are the more important it is. This is because as we now know deep sleep promotes both growth and development.

You also tend to get less deep sleep as you age. The amount each person gets will range from one-eighth to one-quarter of their total night’s sleep.

So, if you’re under the age of 30 you may get up to two hours of deep sleep a night, whereas being over 65 you may be limited to just half an hour of deep sleep, or even none in some cases.

The most common sign of a lack of deep sleep, as I alluded to above, is to wake up feeling exhausted even if you have slept for the nominal amount of hours.

And Now For REM Sleep

We go through the sleep cycles in a particular order, non-REM sleep (stages 1-4) and REM sleep (stage 5). And these sleep cycles continue throughout the night until we eventually wake up in the morning.

However, even though REM sleep accounts for 20%-25% of our overall sleep, the phases will get progressively longer as the night goes on.

So, the first phase of REM sleep typically lasts no longer than 10 minutes, whereas the final phase may last for up to 60 minutes.

We are aware that both the brain and body go through various changes during REM sleep, which include:

  • Rapid eye movement
  • The face and limbs will twitch
  • Increased heart rate, blood pressure, and brain activity (the levels of which are very near to when we are awake)
  • Certain changes in body temperature
  • Both the arms and legs are literally paralyzed (known as atonia)
  • Plus sexual arousal is heightened for both sexes

A lack of REM sleep can affect you in a number of ways, such as impacting your cognitive performance, make your memory worse, put you in a bad mood for no apparent reason, and it messes with cell regeneration.

How we perceive pain can also be influenced by a lack of REM sleep.

You could have two people with literally the same injury, but the person who isn’t getting enough REM sleep will perceive the pain to be a lot worse.

Basically, a lack of REM sleep has a way of messing with the brain.

The Final Verdict

So, let’s quickly review the different stages of sleep:

  • Stage 1 or light sleep is simply when you begin the process of falling asleep and doesn’t last very long at all (in some cases about 5 minutes). This is also the easiest stage of sleep to be awoken from without it causing any real issues.
  • Stage 2 or the second stage of light sleep is the longest phase of sleep throughout the night, probably just over 50% of your night’s sleep is in this stage. However, it is still very easy to be awoken from. This is when the body is preparing itself for deep sleep.
  • Stage 3 and 4 or deep sleep and very deep sleep is when the body goes through the maintenance and repair process, and this is the stage of sleep you require to feel refreshed again the following day.
  • Stage 5 or REM sleep is when we dream. It is this stage of sleep that is essential when it comes to retaining memories and learning material. A lack of REM sleep will typically affect the brain in such a way you may suffer many emotional and physical hardships, and in some cases this can actually contribute to premature death.

Well the decision obviously goes down to points when it comes to the battle of deep sleep vs REM sleep, but I’m not going to disappoint you and call it a draw.

Deep sleep is especially important when it comes to our physical wellbeing, whereas REM sleep takes care of the brain and the mental side of things.

However, physical perfection is of absolutely no use to anyone if the brain isn’t functioning properly.

So, it’s a split decision on the judges’ cards, but the winner is…

REM Sleep.

Thanks you for reading.

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2 thoughts on “Deep Sleep vs REM Sleep – A Fight For The Title Belt, Who Wins?”

  1. Hey,

    This is a really interesting article and I like how you’re organised it as a boxing match between REM and deep sleep. Since lockdown I have had a mixture of REM kind of sleep and deep sleep. I think I am sleeping deeper because I have become lazier, and for some reason you feel more tired when you are lazier. However, I have also been waking up every couple of hours, mainly because I have things on my mind.

    It’s great to find out what is actually happening during both types of sleep.

    Thanks for sharing and keep up the great work.

    All the best,


    • Hi Tom,

      Always great to hear from you.

      I think with the current covid-19 pandemic and the imposed lockdown, a lot of people are struggling to sleep.

      I think it’s even more important to keep as active as possible during the day, so you can tire yourself for bedtime.



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