REM vs NREM: Difference and Comparison

Sleep is an essential component of our existence. It boosts both physical and emotional well-being. There are two types of sleep: REM sleep and non-REM sleep.


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A variety of things, including diet and room temperature influences the quality of your sleepsult a physician if you believe you may be suffering from a sleep disorder. Sleep disturbances can be treated in a variety of ways.  

Key Takeaways

  1. REM sleep involves vivid dreams and rapid eye movement, while NREM sleep lacks these features.
  2. NREM sleep promotes physical restoration, whereas REM sleep supports memory consolidation and emotional regulation.
  3. Sleep cycles alternate between NREM and REM stages, with REM periods increasing in duration as the night progresses.


REM (Rapid Eye Movement) sleep is characterized by fast brain waves and increased physiological activity, including rapid eye movements, increased heart rate, and irregular breathing. Slow brain waves and decreased physiological activity characterize sleep in NREM (Non-Rapid Eye Movement).


The Rapid Eye Movement stage is one of the deepest stages of sleep. It consumes roughly a quarter of your sleep time.

At first, REM occurs in small bursts that last only a few minutes but gradually extend into more significant time segments. REM sleep is beneficial to your memory. Even when the eyes are closed, they move quickly from side to side. 

NREM refers to all stages of sleep that aren’t REM. The body can move while the eyes remain fixed.

Stages of sleep range in intensity from stage 1 (lightest) to stage 4 (deepest) (deepest). Deep sleep occurs in stages 3 and 4, where the majority of the physical repair happens. In NREM, growth hormone is generated, and cellular repair starts. 

Comparison Table

Parameters of Comparison REM NREM 
Full-Form Rapid Eye Movement Non-Rapid Eye Movement 
Stages It is not classified into stages. Dreams are prevalent and vivid. 
Dreams Dreams are very common and vivid. Dreams may occur in the third stage but aren’t as vivid or memorable. 
Eye Movements Eye movements are very evident and noticeable. Dreams may occur in the third stage but aren’t as vivid or memorable. 
Energy Consumption Uses more energy Uses less energy 

What is REM? 

REM sleep occurs approximately an hour and a half after you fall asleep. The first REM cycle lasts about ten minutes.

The duration of each consecutive REM stage increases, with the final one lasting up to an hour. Both your respiration and pulse rate speed up. There is a lot of dreaming going on. 

You are also more likely to have vivid dreams during REM sleep because your brain is more active. REM is significant because it stimulates parts of the brain that aid learning and is linked to increased protein synthesis. 

Adults spend just approximately 20% of their sleep in the REM state. However, babies can spend up to 50% of their sleep in this stage. After passing through stages one, two, and three, the brain enters REM sleep, which lasts about 90 minutes.  

When you enter REM sleep, your brain activity spikes again, indicating that your sleep isn’t as profound. The levels of activity are similar to when you’re awake. As a result, REM sleep is when you’ll get the most vivid dreams. 

During REM sleep, your body undergoes a range of changes in addition to heightened brain activity and muscular relaxation.  

Brain activity increases during REM sleep, voluntary muscles are blocked, and fast eye movements and dreams ensue. The following section delves more into REM sleep and the features of the various stages of non-REM sleep. 

What is NREM? 

Non-REM sleep is divided into three stages. Each stage might last anywhere between 5 and 15 minutes. Before you attain REM sleep, you must go through all three phases.

The physiological activity of non-REM sleep is reduced as bodily movements slow down. Non-REM sleep is divided into three stages, which are referred to as N1, N2, and N3. 

The three different stages of NREM sleep are as follows:  

  • Stage N1 lasts only a few minutes and happens quickly after you fall asleep, and consists of a light sleep that you can be easily woken up from.  
  • The N2 stage lasts 30 to 60 minutes. Here, your muscles will relax, and slow-wave brain activity can be noticed.  
  • The N3 sleep stage lasts 20 to 40 minutes and is characterized by deep sleep. Delta brain activity intensifies at this stage, and a person may move their body. It is extremely difficult to rouse someone at stage N3. 

Each stage has its own distinct characteristics, such as the depth of sleep or the degree of sensory and motor dissociation.  

The body heals and regrows tissues, creates bone and muscle, and boosts the immune system during the deep stages of NREM sleep. 

Electrical activity in the brain slows down during non-REM sleep, growth hormone is secreted, and muscle activity, heart rate, respiration, and oxygen consumption all decrease.

Many brain regions, including the thalamus and cerebral cortex, govern non-REM sleep. 

Main Differences Between REM and NREM 

  1. The full form of REM is Rapid Eye Movement, and the full form of NREM is Non-Rapid Eye Movement. 
  2. REM is not divided into stages; NREM is classified into 3 stages. 
  3. In REM sleep, dreams are very common while vivid and memorable, whereas in NREM sleep, dreams may only occur in the third stage and aren’t as vivid or memorable. 
  4. Eye movements are very noticeable and evident in REM sleep. However, they aren’t noticeable during NREM sleep. 
  5. REM sleep requires more energy than NREM sleep. 


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