Myth or Fact: Deep Sleep Isn’t As Important as REM Sleep

16th April 2019

Read time is about 6 mins

Myth or Fact: Deep Sleep Isn’t As Important as REM Sleep

Until relatively recently in human history, we thought that all sleep was the same. We also believed that our brain was completely inactive while we rested.

It wasn’t until the 1930s when we discovered what sleep stages were, thanks to the invention of the EEG (electroencephalogram) machine. This was a defining moment in sleep science, because scientists discovered sleep is actually a dynamic activity; not only are our brains not turned off, but in fact are highly active.

Every sleep stage is important, but are they all equal?

REM (rapid-eye movement) sleep gets a lot of attention, since it’s arguably more “interesting”. REM is the dreaming stage, and humans have long been fascinated by dreams. With REM seeming to be a lot more exciting and active, we might overlook the stages, including deep sleep.

Today, let’s dive into deep sleep, and learn why it matters.

What are the benefits of deep sleep?

The benefits of deep sleep (also known as delta sleep, slow wave sleep, or N3 sleep) are still quite mysterious; what we do know, is that there are both physiological and psychological benefits.


Deep sleep is the stage when you’re the most disconnected from your environment. Your heart rate slows, along with your breathing, your muscles relax, and there is very little movement. On the inside, however, things are very active!

Muscle repair, healing and growth happens primarily during deep sleep. Your organs, in particular your liver, are also very active at this time; it’s when your liver detoxifies, breaks down adrenaline, and manages your blood sugar levels (source). It’s also during deep sleep that your kidneys clean your blood.

Often we see that people who are suffering from a sleep disorder, such as Obstructive Sleep Apnea, will not get enough deep sleep (or sometimes none at all) which is debilitating to your daily functioning, ability to recover and concentrate. Hint: If you think you’re suffering from Sleep Apnea, click here to get a complimentary sleep assessment.


Deep sleep is considered the most “refreshing” stage of sleep. Insufficient deep sleep, or interrupted deep sleep, can lead to grogginess. That’s why when someone wakes up during the deep sleep stage, they can be disoriented.

Memory consolidation – the creation of new memories – requires deep sleep, too. Insufficient amounts of deep sleep has been linked to memory troubles, and diseases like Alzheimer’s.

How much deep sleep do you need?

We spend more time in deep sleep earlier in the sleep cycle, and move towards more time spent in REM as the night progresses. In terms of how much deep sleep you need, there isn’t a specific requirement, but we need more in our youth than we do in adulthood.

Individuals under 30 may spend two hours or more in deep sleep, while people over 65 may only get half an hour or less. Most scientists think this may be because deep sleep promotes growth and development. It makes sense that younger people, who are still growing and developing, need more time spent in this stage.

How do I increase time spent in deep sleep?

While we can’t force our brain into any particular stage of sleep, there are some strategies you can try to increase the amount of time you spend in deep sleep:

  • Reducing your stress levels
  • Blocking out light (don’t miss last week’s article on artificial light!)
  • Meditating before bed
  • Keeping your bedroom cool (around 16 degrees Celsius is ideal)
  • Getting enough exercise 
  • Establishing a bedtime routine 
  • Treating your sleep disorder (such as insomnia or sleep apnea)

In order to get a more accurate picture of your total sleep time, a sleep study can show how much time you spend in each stage! Book your free sleep study today!


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