What is REM Sleep?

The Science of Sleep: What is REM Sleep and Will a Good Mattress Help?

On average, a person spends one-third of his or her life sleeping, and getting quality sleep during this time is crucial to one’s health and overall wellbeing.

Every night our heads hit the pillow, and we fall asleep, and every morning we wake up to start our day. Most people give little thought to what happens between the time we close our eyes and the time the alarm clock goes off in the morning.

In actuality, sleep is an essential part of well-being and plays a vital role in both mental and physical health. All sleep is not created equal, and sleep has distinct stages which have specific purposes.

Key Point: Rapid eye movement (REM) sleep is of particular importance when it comes to mental functions such as emotional regulation, memory formation, and making unique brain connections.

What Is REM Sleep?

REM sleep is a distinct phase of sleep where the brain is highly active, and it is the time when the majority of dreaming occurs.

During this stage of sleep, a person’s eyes move side to side, which gives rise to the name of this sleep stage.

Heart rate and breathing rate increases, while most of the muscles of the body are paralyzed to avoid acting out dreams and injuring yourself.

REM sleep has the unique function of making new brain connections, which is why some of our dreams are so strange and often do not make rational sense (Lee-Chiong, 2008).

REM sleep occurs in intervals. The first interval is the shortest in duration and occurs approximately 90 minutes after falling asleep.

Each subsequent REM interval is longer, with the most prolonged interval lasting about 30 minutes. Altogether, a person generally spends 25% of sleep in REM.

Key Takeaway: It is crucial to get the optimal eight hours of sleep per night because toward the end of the night; you spend more time in REM sleep compared to non-REM sleep. If sleep is disrupted or shortened, the full benefit of REM sleep will be missed (Walker, 2018).

What Is Non-REM Sleep?

Between REM cycles, non-REM (NREM) sleep occurs. Non-REM sleep is composed of four different stages of sleep.

Stage one of NREM sleep is characterized by relaxed wakefulness, in which a person is vaguely aware of what is happening around them.

Many physiological processes start to slow down, including your brain waves, breathing, pulse, and blood pressure.

The second stage of NREM sleep is where people spend the majority of their sleep cycle. You can think of this stage of sleep as the transition stage into a deep sleep.

Stages three and four of NREM are considered deep sleep and are characterized by delta (very slow) brain waves. NREM sleep is associated with getting rid of old memories, known as pruning, and with solidifying new memories (Walker, 2018).

The Science of Good Sleep: What is REM Sleep and Why is it Important?

Importance of REM Sleep

REM sleep is the time when the brain restores itself and is, therefore, a critical process in maintaining emotional and mental well-being.

During REM, the areas of the brain that are responsible for learning, decision making, memory formation, and emotional regulation are active.


During REM, the brain consolidates memories, which means it converts new experiences and newly acquired information into long-term memories.

The brain communicates messages to other areas of the brain by sending electrical impulses. These electrical signals move quickly in all directions, which allows for unique and novel connections to be made during this stage of sleep.

When you hear about people waking up from sleep with an answer to an unsolved problem or an idea for a new invention, you can thank REM sleep for facilitating this process.  

Emotional Processing

One of the significant activities that occur during REM sleep is emotional processing. It is during this time that the amygdala, the part of your brain that handles emotions, fear, and memory, makes sense of your day’s events, including your interactions with other people and your environment.

REM sleep allows your amygdala to process negative emotions, in particular, fear and stress, without causing your brain distress. REM sleep is essential for balancing emotional reactivity.

Deprivation (loss) of REM sleep, such as REM fragmentations where REM is interrupted by short awakenings, is associated with the accumulation of negative memories, an increase in emotional reactivity, as well as negative emotional intensity. Both depression and PTSD are related to interrupted REM sleep (Pesonen, 2019).

Causes of Interrupted REM Sleep

Our sleep cycles can be disrupted by many factors, such as stress, alcohol, and medications.

What is REM sleep?

Chronic stress increases the release of the stress hormone cortisol, which interrupts the natural sleep cycle. High levels of cortisol can lead to frequent waking at night and morning grogginess (Bassett, 2015).

In addition to stress, mood disorders such as depression are associated with interrupted REM sleep. This interruption creates a perpetuating cycle since a disturbed REM sleep worsens depressed mood (Pesonen, 2019).

Sleep apnea is a common cause of frequent waking. It occurs when a person stops breathing for a short time, subsequently causing the normal levels of oxygen supply to be reduced. This condition is commonly treated with a C-pap machine which ensures an adequate supply of oxygen is delivered to your body.

Issues with falling or staying asleep are frequently self-medicated with alcohol or treated with benzodiazepines, such as Xanax, and sleep aids like Ambien by your doctor. Unfortunately, all of these interrupt REM sleep, which negatively affects cognition, mood, and general functioning during the day.

There are alternative approaches to help decrease the time it takes to fall asleep, such as melatonin, a natural hormone released by a structure in your brain involved with falling asleep. Additionally, implementing proper sleep conditions and adequate sleep-promoting habits improves sleep quality and quantity for the majority of people without the use of sleep medications or sedatives such as alcohol.

Improving REM Sleep

There are many ways to improve the amount, frequency, and quality of your sleep. Insomnia is the most common sleep disorder reported with over a quarter of the US population suffering from acute insomnia (“Sleep Statistics-Data About Sleep and Sleep Disorders,” 2018).

With this many individuals suffering from insomnia and difficulty falling asleep, we should be educating ourselves and our children on proper sleep hygiene and the importance of getting a good night’s sleep.

Improving REM sleep

Tips for getting a good night’s sleep:

  • Make sure your room is free from electronics and other distractions
  • Use your bedroom only for sleeping
  • Go to bed at a specific time at night and wake at a particular time in the morning
  • If you are having trouble falling asleep, get out of bed and do something until you feel tired
  • Avoid caffeine, other stimulatants, and alcohol before bed
  • Meditate or perform focused breathing before heading to bed

To summarize, quality sleep is fundamental to optimal cognitive performance, memory, emotional regulation, and general health. REM sleep is a critical part of the sleep cycle involved with dreaming, emotion regulation, memory, and making new unique connections.

Substances such as alcohol and sleep medications as well as conditions such as anxiety, chronic stress, and depression can interfere with REM sleep, causing problems optimally functioning during the waking hours.

Since we spend about a third of our lives sleeping, we should educate ourselves about the processes involved in sleep and the ways to get the maximal quality of sleep. Quality sleep will improve your overall daily functioning, relationships, health, and memory. 

How a Good Mattress can Improve REM Sleep

When you feel uncomfortable while sleeping on your mattress, your discomfort will affect your body’s ability to reach the REM cycle. Fortunately, a good mattress is sometimes all it takes to improve your REM sleep!

First, your spine will be in a neutral position so you can wake up with less soreness, tenderness and pain in your body. Your body and brain will be in perfect sync so you can transition better into the REM stages.

Second, your body will be more comfortable, temperature-wise, with a mattress that promotes better temperature regulation. When you sleep, your body’s automatic thermoregulation process becomes less efficient during REM sleep. The materials used in the mattress, from the foam to the fabric cover, should then promote a cool and comfortable feeling.

The bottom line: You must change your mattress, when necessary, since its overall condition will affect your REM sleep and, thus, your overall health!

When Is It Really Time to Change Your Mattress?

Standard rule dictates that you should change your mattress at least seven years after its purchase; 10 years is the recommended maximum. But don’t wait for the 7-year rule to buy a new mattress either, even when you still seem to sleep fine on it!

When a few or all of these defects are seen on your current mattress, then it’s time to change it.

  • Obvious sagging, usually caused by springs breaking, latex foam being compressed, or memory foam becoming softer
  • Impression left by your body on memory foam stays for far longer than before or when it’s more than two inches in depth
  • Significant change in firmness in memory foam, either too soft or too hard
  • Lumps resulting in uneven mattress surface and density
  • Increase in allergic reactions, a presence of colonies of mold, dust mites, and mildew

The most obvious sign: If you wake up like you’ve never slept at all – or worse, you weren’t able to get a good shut eye the entire night – and your body aches in places, then your mattress may be the culprit.

But you may also be the culprit in that your body or life has undergone significant changes – weight gain, injury or illness, or a new bedmate. In this case, get a new – and right – mattress already!

What Else Can You Do for Better REM Sleep?

Your new mattress is just one part of the equation. You should consider these steps, too.

  • Change your pillows so that these provide sufficient head, neck and shoulders support.
  • Ensure the right sleeping conditions in your bedroom, such as turning off the lights and blue light sources and maintaining a cool and comfortable temperature.
  • Develop good sleeping habits. A regular sleep schedule, a relaxing sleep routine, and avoidance of caffeine, alcoholic drinks and tobacco before bed are a good place to start.


  1. Bassett, S. M., Lupis, S. B., Gianferante, D., Rohleder, N., & Wolf, J. M. (2015). Sleep quality but not sleep quantity effects on cortisol responses to acute psychosocial stress. Stress, 18(6), 638-644.
  2. Irwin, M., McClintick, J., Costlow, C., Fortner, M., White, J., & Gillin, J. C. (1996). Partial night sleep deprivation reduces natural killer and cellular immune responses in humans. The FASEB journal, 10(5), 643-653.
  3. Lee-Chiong, T. J. (2008). Sleep medicine : Essentials and review. Retrieved from https://ebookcentral-proquest-com.lopes.idm.oclc.org
  4. Markwald, R. R., Melanson, E. L., Smith, M. R., Higgins, J., Perreault, L., Eckel, R. H., & Wright, K. P. (2013). Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain. Proceedings of the National Academy of Sciences, 201216951.
  5. Pesonen, A. K., Gradisar, M., Kuula, L., Short, M., Merikanto, I., Tark, R., … & Lahti, J. (2019). REM sleep fragmentation associated with depressive symptoms and genetic risk for depression in a community-based sample of adolescents. Journal of affective disorders, 245, 757-763.
  6. Walker, M. P. (2018). Why we sleep: The new science of sleep and dreams. London, UK: Penguin Books.
  7. Sleep Statistics – Data About Sleep and Sleep Disorders
  8. (2018). American Sleep Association. Retrieved 23 May 2019, from https://www.sleepassociation.org/about-sleep/sleep-statistics/
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Dr. Kasey Nichols, N.M.D.

Dr. Kasey Nichols, N.M.D. focuses on sleep disorders and drug-free pain management utilizing both conventional and alternative medicine at his private practice, Onyx Integrative Medicine and Aesthetics, located in Gilbert, AZ. He served as the Director of Medical Operation and Administration at a national substance abuse disorder corporation with 16 facilities across seven states. He graduated from Cleveland University-Kansas City with a Bachelor’s of Science in Human Biology, graduating with honors, and holds a Doctorate from The Southwest College of Naturopathic Medicine. He holds licenses in both Arizona and Kansas. Dr. Nichols has given numerous talks to professional organizations, given interviews for newspapers across the United States, and numerous television news interviews with ABC 15/CW 61 in Arizona, Channel 3 in Arizona, and others. Dr. Nichols has appeared in Cosmopolitan, Reader’s Digest, WebMD, Healthline, and many other health and lifestyle publications.