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What Is REM Sleep Anyway?

What Is REM Sleep Anyway?

Even if your first awareness of the term REM was from humming along to the early 90s classic “Losing My Religion,” we’re sure you’ve heard of REM sleep before. Whether you’re a fan of the rock band or of what people commonly refer to as the “dream state,” you likely already know that REM stands for rapid eye movement, too.

But, REM is about more than just dreaming and rapid eye movement. It’s actually an important stage of sleep that your brain and body need – a lot.

A good night’s rest depends not only on how many total hours you sleep, but also on how much time you spend in each stage of the sleep cycle. That means that even if you got a solid eight hours, you’re not guaranteed a restorative night of sleep unless you’re spending an adequate amount of time in each stage – especially deep sleep and REM.

Why is the REM sleep stage so vital and what even happens during REM sleep? Let’s break it down.

What are the sleep stages?

Like we said, REM is just one piece of the sleep puzzle. So, let’s get a better sense of that puzzle first. In terms of sleep stages, there are a total of four in the sleep cycle:

  • Stage 1 = non-REM sleep where you are between awake and asleep or in a state of very light sleep
  • Stage 2 = non-REM light sleep that is slightly deeper than Stage 1 where body temperature begins to drop and heart rate slows
  • Stage 3 = non-REM deep and restorative sleep (also known as slow-wave or delta sleep) where muscles relax, blood supply increases and the body and brain begin to repair themselves
  • Stage 4 = the REM sleep stage, which is only entered following the above stages and is most commonly associated with dreaming
Young woman in striped pajamsas sleeping on her backYoung woman in striped pajamsas sleeping on her back

What happens during REM sleep?

Rapid eye movement (REM) sleep is also known as active sleep, desynchronized sleep, paradoxical sleep or dream sleep. During REM sleep, your eyes move rapidly behind your closed eyelids, your heart rate speeds up and your breathing may become irregular.
Unlike the other stages of the sleep cycle where everything is slowed and steadied, the brain is highly active during REM – hence the ability to dream. In fact, our brain wave during REM sleep is fairly similar to when we are awake! We also lose complete muscle tone and are more prone to being woken up during REM sleep as opposed to non-REM sleep.

5 Major benefits of REM sleep 

While all stages of the sleep cycle are important and depend on one another, REM sleep is particularly important. Here’s why:

  1. Dreaming: The majority of our dreams take place during REM sleep and are most vivid during this sleep stage. Dreams can be fun! (Psst … they serve a purpose, too, keep reading!)
  2. Emotional Processing: The amygdala, which is the part of the brain that processes emotions, is activated during REM. Your brain is quite literally making sense of your feelings while you sleep – convenient, right?
  3. Memory: The brain processes new information from the day and commits it to memory during REM sleep. It helps us learn new skills and information, consolidate memories and solve problems.
  4. Brain Development: Newborn babies spend the majority of their sleep cycle in REM sleep, so it has been hypothesized that brain development is dependent on REM sleep.
  5. Preparation to Wake: REM sleep activates our central nervous system and prepares us for being woken up. Without it, you’ll experience that unshakeable grogginess.

Not getting enough REM sleep? There are risks! 

Woman lying on her side in a deep restorative sleepWoman lying on her side in a deep restorative sleep

Lack of (or even diminished) REM sleep can interfere with the brain’s emotional processing, memory formation and even its ability to generate new cells. How much or how little REM sleep we receive plays an active role in our daytime brain function.

REM deprivation, or dream deprivation, can lead to fatigue and drowsiness during the day, which can impact our:

  • Work performance
  • Relationships
  • Overall health

Because this stage of sleep supports our ability to process emotions, those who don’t get enough of it may have a harder time working through complicated feelings, leading to an increased risk for anxiety and depression. REM sleep loss can also result in increased inflammatory response, rick for obesity, migraines and chronic insomnia.

What interferes with REM sleep?

A better question might be: what doesn’t? There’s no shortage of exposures that have the potential to disturb REM sleep and the sleep cycle in general. Some of common offenders are:

Woman drinking a glass of wine, which could disrupt REM sleepWoman drinking a glass of wine, which could disrupt REM sleep


  • Alcohol –While it can be fun to relax with a drink, alcohol, a nervous system suppressant, disturbs the quality and structure of sleep. Often, REM sleep is interrupted the morning after a night out (you’ll feel it as a sudden jolt awake.)
  • Cannabis – Similar to alcohol, cannabis is also a nervous system suppressant with sedative properties. While it may aid in sleep onset, it suppresses REM sleep with habitual use.
  • Sleeping Pills – Prescription sleep medications result in less restorative sleep and suppress REM sleep altogether. And, beware, this is rarely listed as a side effect!
  • Antidepressants – These prescription meds can significantly suppress REM sleep. If you suffer from depression, don’t let that sway you from seeking help! Just be sure to discuss any sleep issues with a mental health professional.

Other factors that may interfere with REM sleep include exposure to artificial blue light and waking artificially from an alarm clock.

Luckily, there are also a ton of things you can do improve your sleep hygiene and get better sleep at every stage of the sleep cycle. Try practicing yoga for sleep or taking daily walks. Making changes to your diet or taking Vitamin D supplements can also help. And – sorry not sorry – but of course we also need to tell your that a healthier mattress leads to healthier sleep!