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Memory Foam Pillow and its Amazing Benefits

From daily pressures and significant life changes to excessive use of electronics, the reality is that many individuals are lacking in sufficient restful sleep. To achieve that rejuvenating rest, selecting the right pillow can play … Read more

Written by:

Derek

Last Updated: Fri, May 2, 2025

From daily pressures and significant life changes to excessive use of electronics, the reality is that many individuals are lacking in sufficient restful sleep. To achieve that rejuvenating rest, selecting the right pillow can play an important role.

Accordingly, some of the most popular for those wanting to upgrade where they rest their head every night are contoured pillows made out of memory foam. These types of pillows are ideal for those dealing with neck pain.

People are drawn to memory foam for all sorts of different reasons, but one of the biggest attractions is the way the material conforms to pressure.

Memory foam is engineered to cradle you in a way that helps your head to stay in healthy alignment with your spine. It is also built to be durable, resilient, and support you all night long without caving in over the course of your slumber.

Memory Foam Pillow

Memory foam is a special type of material which reacts to temperature and pressure which causes it to mold and conform to shape accordingly.

Therefore, the foam creates a mold around the shape of your head, neck, shoulders, ears and any other body part which it comes into contact with when it comes to sleeping on bed pillows.

The traditional and most common type of foam is polyurethane, also known as viscoelastic foam. There is also another variant which includes a portion of gel, but this type has thousands of small gel beads in its mix.

The gel memory foam pillow is newer on the scene, slightly more expensive, and has its benefits over its peers through lesser heat retention thus allowing a more cooling sleep surface.

Urban legend has it that NASA invented memory foam in the 1970s to cushion the astronauts on space flights.

While NASA says that it did have a hand in the development of memory foam, Charles Yost is credited with the invention while under contract with NASA in 1966 to use in airplanes.

The viscosity of the foam allows your body heat to soften the pillow which supports your head, helping alleviate neck and back pain.

Based on the heat from your body, Memory foam pillows work and soften into the ideal shape to support your head and neck. There are several ways to use a memory foam pillow to improve your sleep.

To provide maximum support for your head and neck, regardless of whether you sleep on your side or your back, place the flat side of your pillow down and orient the pillow with the larger of the two curves toward the foot of your bed.

Settle into your pillow and effortlessly let your head sink in. Stay with it even if the pillow seems too hard at first.

In a few minutes, you will feel the pillow conform to your head, neck, and shoulders due to your body heat. Note that it will take a little while for the foam to change position when you do.

As the foam cools, it becomes stiffer. This is an ideal time to take a few cleansing breaths or to meditate for a few minutes to prompt your body and brain to have a deep and stress-relieving sleep.

Sleeping on your stomach with a memory foam pillow is not highly recommended. The pillow’s unique shape can put a stomach sleeper’s head and neck at unusual angles, which can increase neck pain and headaches.

Regardless of the type of pillow you use, sleeping on your stomach can cause you to awaken with a stiff neck and can negatively affect your shoulders, upper back, jaw, and vital organs.

Memory foam pillows, regardless of the position you prefer to sleep in, can help you have a better rest each night, even if it means teaching your body not to sleep on your stomach.

Types of Memory Foam Pillow

Unlike other types of pillows and designs such as buckwheat or down, memory foam pillows come in various shapes and styles.

Ultimately, they are all for laying your head down for a good night’s sleep, but which one you’ll choose depends on more specific needs, as each one serves a slightly different purpose.

Contour

A contour memory foam pillow is a slab of viscoelastic foam which has two ridges running horizontally from one side to another and a subtle groove.

The groove is where the head is cradled, and with the ridges supporting the neck, it provides maximum stability for the head too.

Due to the contoured shape combined with the supportive nature of viscoelastic foam, it is a very popular choice for those with neck problems and is similarly also considered one of the best pillows for back sleepers too.

Shredded

A shredded memory foam pillow is entirely different from the aforementioned contour style pillow. In terms of shape, they are usually rectangular, similar to that of the traditional types.

They are referred to as shredded because the interior consists of hundreds or sometimes thousands of tiny shreds of foam pieces compacted together to form the filling.

The benefits of having this shredded nature are that it allows the foam to be more breathable thus making it sleep cooler and not creating a heat trap.

Additionally, although there is no real need to fluff, a shredded memory foam pillow can have its loft adjusted or be scrunched and molded to shape a little if required, unlike a contour pillow.

Traditional

It’s the relatively low loft rectangular shaped ones which you’re most likely to be familiar with when we refer to the term “traditional”.

When it comes to foam pillows, there are two very similar variations in particular which are the most popular. Both are one-piece and cut to size.

The first is genuinely traditional in that it’s tailored by a single seam around all four edges, and has slightly sloped or angled edges which are common in a majority of bed pillows.

The second is also similar in shape and size to the former but instead has a double seamed edge which allows for a consistent and higher loft especially around the edge.

These are known as a gusset pillow, and due to the high loft and increased support for the neck and shoulder area, they are widely accepted as all-around top rated pillows.

Wedge

A wedge pillow goes by many different names and has more uses than the traditional rectangular shaped types.

Basically, a memory foam wedge pillow is shaped like a giant triangle. It is slanted with a gradual slope and is commonly used to prop the body up for different purposes.

Typically, the size and angle of the slope greatly determine its usage and whether it’s for adults or babies. Due to the conforming and heat retaining nature of this material it can be an extremely comfortable and warm surface to lay back on.

Recommended extensively for medical reasons such as respiratory problems, acid reflux or sinus issues, wedge pillows aren’t just used for sleeping.

Also known as a bed wedge, they are a popularly used as a reading pillow while sat upright and leaned against.

Alternatively, they can also be used to elevate the lower body by placing underneath the back of the knees which helps reduce the load on the lower back.

Additionally, they are also perhaps regarded as the best pillows for pregnancy considering they can be placed under a baby bump to reduce stress on the lower back.

Benefits of Using a Memory Foam Pillow

Durable

Memory foam pillows hold their shape and are less likely to go flat like traditional pillows. The foam conforms to fit the head and neck, but when it cools down, it goes back to the original shape.

Hygienic

Memory foam is a synthetic material and is safe. These pillows are hypoallergenic which obstructs the growth of bacteria and dust mites. This is a benefit for those who experience allergies to features and dust mites.

If you have suffered from allergies for a long time and have yet to come across any form of relief, the problem may be resting beneath your head.

Traditional goose-down, duck feather, and even synthetic pillows have been widely known to cause allergic reactions.

Most traditional feather pillows contain dust mites and millions of fungal spores that create miniature ecosystems within your pillows.

These tiny beings, combined with your sweat as you sleep make for a hotbed of bacterial growth that leads to problems with allergies.

The most long-term and optimal solution by far is to opt for a safer and more hypoallergenic option, like the memory foam filled pillow.

Pressure Points

Memory foam pillows are designed to outline the unique shape of the body and support your neck and heat. The foam reforms where it is not pressured, and more where the stress is increased.

Sleep Apnoea

The advantages for those with sleep apnoea are obscure. But, it is believed that the spinal alignment aligns the airways better and allows for easier breathing.

The shortage of pressure points with memory foam may benefit those with sleep apnoea because there will be less tossing around.

Spinal Alignment

Back pain or headaches are usually caused by poor spinal alignment. One of the major health benefits of memory foam pillows is spinal alignment.

When your head and neck is placed on the pillow, the warmth of your body allows the foam to reshape itself.

Side Sleepers

For many years, pillows have been filled with duck and goose feathers that, while soft in the beginning, compress throughout the night, leaving your head to rest on a flatbed of fluff.

The lack of support found with down pillows has led some traditional users to experience unsavory health complications. Specifically, for those who mainly sleep on their sides, it’s common to experience stiff necks each morning due to improper alignment of the spine.

The optimal position for the neck during rest is what experts call the “neutral” position. This is when that natural curve of the neck is at the perfect and comfortable angle, so as not to overly bend or compress the joints.

For this ideal alignment of the neck to occur, it’s best to find one that is thick enough to allow your head to rest gently and evenly within the “neutral” position.

Neck Pain Relief

The need to ease neck pain is one of the main reasons to switch to a different pillow. Another reason to think about switching is that Cervicalgia is the cause of many more serious health issues over time.

While this pain can be the result of many factors such as car crashes, sports injuries or genetics, using the wrong neck support for these pre-existing conditions only serves to exacerbate the problem by inflicting tension and stress on the neck and back.

It is imperative that your neck and head are elevated to a specific height when trying to alleviate neck pain.

Memory foam pillows are a way for you to accomplish this because polyurethane is specifically designed to provide elevated support and a “melting in” feeling that adds to your overall comfort.

Best Memory Foam Pillows of 2019

Coop Home Goods Memory Foam Pillow

The Coop Home Goods memory foam pillow is largely considered to be the most comfortable and versatile pillow you can buy.

It’s filled with shredded memory foam that you can take out or put into the pillow to adjust the thickness and firmness, so it’s totally customizable to your needs.

Inside the pillow, you’ll find Coop Home Goods’ proprietary mix of shredded Visco elastic memory foam which you can add or remove depending on your needs.

The pillow comes with plenty of foam, too, so even those who prefer really thick pillows should be fine with what the Coop Home Goods memory foam pillow has to offer.

Thanks to the fact that the pillow has shredded foam, it is also quite a bit more breathable than most memory foam pillows, so those of you who tend to get hot at night should be all right.

Features and Design

Polyester liner
Viscoelastic polyurethane and polyester fill
Bamboo-derived viscose rayon and polyester case

Pros

Adjustable
Breathable
Relatively inexpensive

Cons

Gives off slight smell for the first few days of use.

Premium Shredded Foam Pillow

Brooklyn Bedding is known for selling American-made mattresses, but the company also offers bedding accessories, including excellent memory foam pillows.

The Premium Shredded Foam pillow claims to offer the “best value” along with “cloud-like comfort with contoured support.”

The pillow comes with a removable cover that is machine washable, moisture wicking, and anti-microbial for a more hygienic sleep environment.

If you find it to be too thick, the pillow itself unzips so you can remove some of the foam as needed. The inside is made up of shredded memory foam and latex and is designed to draw heat out and away from your head as you sleep.

Features and Design

A blend of deconstructed high-quality foam is encapsulated in a zippered cover for easy removal, allowing sleepers to adjust loft for a super personalized sleep experience.
A cooling gel foam infusion in deconstructed foam draws heat out and away from the head and neck areas for an exceptionally cool night’s sleep.
A moisture-wicking, anti-microbial cover provides a dry and hygienic sleep environment perfect for sensitive skin.
Made in the USA.

Pros

Affordable
Soft yet supportive for side and stomach sleepers
Height can be adjusted
Comes with machine washable case

Cons

May not offer enough support on its own for back sleepers

Bear Pillow

The Bear Pillow’s signature Loft-X Foam isn’t quite as firm or stiff as a lot of other memory foam pillows, which prevents it from leaving you with a crooked neck in the morning.

The Bear Pillow also comes with a removable, washable, antimicrobial or hypoallergenic cover which you could buy separately.

This is a great pillow for those who sleep hot, and users claim to actually be able to feel air passing through the pillow, which suggests that the mesh panels are doing their job. The pillow also feels cold to the touch, thanks to its yarn, which the Bear Mattress company calls “double ice fabric.”

Features and Design

Double Ice Fabric
Loft-X Foam
Dual Mesh Side Panels
Hypoallergenic/Antimicrobial

Pros

Cooling
Well-balanced between plushness and firmness

Cons

May be best without a pillowcase, which might not look so good on your bed
Not easily bunched up or reshaped if you like to fold your pillow

Sleep Innovations Contour Pillow

If you’re looking for a pillow that’s contoured to your neck and head, the Sleep Innovations Contour Memory Foam Pillow is the best choice for you.

The contour pillow is aimed specifically at stabilizing your head during the night, ensuring you wake up feeling refreshed and that you don’t do damage to the muscles in your neck.

Not only is the Sleep Innovations pillow great at managing temperature, but it’s also contoured. It has an inner layer of SureTemp foam, which allows for great airflow during the night.

It also has a cover that’s made of 74% cotton and 25% polyester, and it can be machine washed. The pillow also has a five-year warranty, which is great for those who are looking for something that will last.

As is the case with plenty of other memory foam pillows, you’ll find that there will be a slight odor to the pillow when it arrives, but it’ll go away after a few hours of being aired out.

Features and Design

It provides therapeutic support so you wake up feeling refreshed, recharged and ready to take on the day.
Its cooling memory foam facilitates airflow to keep you comfortable all night long.
Its ergonomic shape and cradling memory foam promote proper spinal alignment and provide support throughout the night to help reduce pain and stiffness.
It is made in the USA.

Pros

Excellent for pain relief
Great temperature control
Pretty inexpensive

Cons

Has a slight initial smell

InteVision Foam Wedge Pillow

For those of you who have issues with acid reflux, breathing difficulties, and poor circulation during the night, a wedge pillow might be the best choice, and the InteVision Foam Wedge Pillow is the best one you can buy.

The InteVision Foam Wedge Pillow has a two-layered design. It has a 1-inch of memory foam on top of the base foam, so it should be comfortable yet relatively firm.

The pillow also comes with a machine washable white cover, and for those who want a pillowcase that will properly fit the pillow shape.

It is relatively durable and good at holding its shape over long periods of time, even with constant use.

However, it’s not great with temperature management and it has an odor when you first buy it. Nevertheless, both are to be expected with memory foam pillows.

Features and Design

This latest version is made of a 2-INCH memory foam layer on top of firm base foam, also adding built-in channels between the top memory foam layer and the base foam to enhance air circulation.
Designed to help patients with acid reflux, snoring, allergies, or any other condition which breathing may be impaired in the supine position
It can also be used when you are recommended by a health professional to sleep in an elevated position after surgery.
The pillow helps reduce back pain which provides a healthy, more comfortable night’s sleep.
Every product comes with the trademark InteVision on its packaging.

Pros

Comfortable two-layer design
Durable
Inexpensive

Cons

Not the best with temperature management

Takeaway

A pillow can make all the difference between getting a good night’s sleep and waking up sore, tired and irritable.

It’s important to know that different sleep positions require different types of pillows to keep your head and neck in a neutral alignment with your spine.

One type of memory foam pillow, despite its many positive qualities, does not fit all. Memory foam is used to fill pillows in a variety of ways, including solid pieces molded into specific shapes or shredded memory foam pieces with a zipper to remove and add as much filling as you like.

Memory foam pillows, for any type of sleeper, are definitely a great option. It’s all about finding the one that is designed around your particular sleep needs.

Our advice would be to narrow down your preferences and search for a pillow that offers trial periods so you can decide for yourself what’s a good fit at little to no risk to you.

Counting Sheep’s Research Process

Written by:

Derek

Last Updated: Wed, March 5, 2025

At Counting Sheep, we’re dedicated to delivering dependable, up-to-date information on sleep health, scientific research on sleep, and products related to sleep. Every evaluation we present is unbiased and based on genuine feedback from consumers. Currently, we’ve compiled over 100,000 reviews from different online sources to develop our fair, evidence-based assessments of various mattresses, pillows, and other sleep accessories. Our experienced team continuously gathers new reviews on a daily basis. Explore how Counting Sheep conducts product research, gathers information, and prepares performance assessments.

Our Sources

We use the following general sources to generate our data, product reviews and ratings:

Forums and Discussion Boards

Around 35% of our data is based on customer experiences, and reviews posted online on different web forums and discussion boards. Research starts by searching for a product review and reading relevant threads within various online communities of all sizes. After reading, our team collects and verifies all information to ensure it’s valid and pertinent to our research.

Retail Product Pages

Around 30% of our data also comes from customer reviews posted to online product pages. We take into consideration online retailers such as Amazon.com, but also B&M brands that sell sleep products and have a strong online presence, such as Target or Walmart. Each review is checked to ensure it’s not fake or that the author has not been compensated for writing it.

Product Review Websites

Around 22% of our data comes from sleep product review websites. Fake or dishonest online reviews sites are not taken into consideration. Our team checks this by finding out whether the owner of the website receives compensation for highlighting certain brands or models or not. Our rule is to avoid sites like these and focus on websites that provide legitimate and objective information and authentic, unaffiliated reviews.

Publicly Available Information

Our data consists of publicly available information; however, we believe it’s important to emphasize that our team of experts never takes into consideration product descriptions or advertising claims that come from brands and product manufacturers. The only information we actually use is detailed product specifications because they help us create accurate brand and model profiles. The details include the following:

Material composition
Country of manufacture
Available sizes
Product availability
Price
Length, width, and thickness dimensions
Care instructions
Weight
Shipping and delivery policies
Sleep trial and return policies (if available)
Warranty information

In-House Product Testing

We currently don’t have in-house testing, but we are planning to use a testing facility in the future for validating the above-gathered customer experience data.

What is NOT included in our data set?

We never use user-submitted reviews. We strongly encourage all visitors to share their experiences with us. However, since it’s hard to validate user-submitted claims, we cannot incorporate these reviews into our rating system.

What Makes Counting Sheep Unique?

Comprehensive

Counting Sheep covers a wide range of sleep products, from mattresses, pillows and bedding, to a variety of sleep accessories. Since many of these products are subject to change regarding pricing, availability, and other factors that are very important to the consumers, we are sometimes unable to collect enough data to generate what we consider to be an accurate product review. However, on Counting Sheep you will find only legitimate, accurate and comprehensive information that was previously checked and validated by our team of experts. You may rest assured you will never find contradictory advice on our site.

User-Friendly

Creating an ideal sleeping environment is not easy, and maybe not even possible considering the myriad of products that are available today. However, our team of specialists can help you optimize it and turn your bedroom into a sleeping sanctuary. Our comparison tool is easy to use and will help you make a decision you won’t regret. When it comes to purchasing a new mattress, we also offer an extensive selection of individual brand and model reviews to help you narrow down your choices. If you are a troubled sleeper, we also provide research-based guides covering a wide range of sleep-related topics.

Accurate

Data accuracy is one of Counting Sheep’s highest priorities. We do everything we can to ensure the information available on our site is accurate and up-to-date. For this reason, we have established specific parameters for our rating process.

Unbiased and Unaffiliated

All the information you see on our site is unbiased and unaffiliated. To further stress this point, we have decided to share our research methodology with our visitors, and we have created an editorial integrity policy that shows how we gather information, communicate with different companies and brands, and similar. If you have any questions, never hesitate to contact us and ask for more details.

We Are Here to Help!

If you are a troubled sleeper, or you need more information about a particular brand and products or any sleep-related topic, please feel free to contact us. A member of our team will respond as soon as possible. We are available 24/7, and our team is committed to ensuring your experience on Countingsheep.com is informative and meaningful.

Where Should You Start?

Depending on your interests, we recommend beginning with one of our three great guides – The Better Sleep Guide, Sleep Condition Research or our Ultimate Mattress Guide. No matter whether you are looking for ways to improve your sleep hygiene or simply interested in selecting a budget-friendly mattress, these guides will help you get all the information you need to make an informed and a wise decision.

Do You Have Questions or Comments?

If you something any inaccurate on our site or something that you think needs to be updated, please reach out to us! We will greatly appreciate your help! We’re working hard all hours of the day to ensure you get the information you need, so please let us know how we can help.

Advertising Disclosure

Written by:

Derek

Last Updated: Wed, March 5, 2025

At Counting Sheep, our goal is to provide our visitors with up-to-date, quality information on everything related to sleep, including various products. We aim to deliver impartial, top-notch information and ensure our visitors receive honest and accurate product assessments, critiques, and sleep guidance.

We have established relationships with many companies and online retailers that are a part of the sleep product industry. Thanks to these relationships we are able to run, maintain, and grow our website, conduct research, and provide our readers with quality and useful information. Access to the content on our site is completely free, and readers don’t need to pay anything to read our guides, reviews, tips, and rankings.

We have taken the following measures to ensure that affiliate relationships that we have with other brands and companies do not have any influence on the content on our site:

– Our writers and other members of the editorial team are not aware of the relationships that we have with specific companies and brands so that everything on our website is completely unbiased.

– We never compel our writers to give intentionally favorable or unfavorable ratings and reviews to any model or brand as our goal is to provide honest, objective and accurate ratings that will benefit the readers. Our affiliate relationships never influence our opinion of the product, and we will never write a positive review just because we were told to.

– All of us are sleep geeks, and we love testing sleeping products ourselves. If we can test a particular model ourselves, we definitely will, and we will write a review based on our experience and unbiased opinion. If we can’t get our hands on an actual product, we will form our ratings based on verified customer experience from a variety of online sources, or interviews with customers. We will never base our opinions about specific models and brands on communications with the employees of the company that makes them.

If you have any questions about our reviews, ratings, sleep guides, and other content on our site, don’t hesitate to contact us for more information.

Daylight Saving Time Contributes to Sleep Loss

Written by:

Derek

Last Updated: Mon, February 24, 2025

Only around 10% of people are really affected by daylight saving. However, we loudly complain about it every year. Many Americans consider the annual switch to daylight saving time a terrible idea. Every year, more and more citizens complain that sleep loss from time changes severely impacts their life.

When the clocks get moved, people usually report being very sleepy and worried that sleepiness may affect their work. Some are afraid of getting into motor vehicle accidents due to lack of sleep, while other report going to the dreamland at inappropriate moments, such as during a meeting. Springing forward can actually do more damage than causing you to lose an hour of sleep. However, there are also things you can do to make the transition less difficult.

How Daylight Saving Time Impacts Our Sleep

When we set our clock one hour ahead when DST begins, do we also set back our health? David J. Earnest, Ph.D., a professor at the College of Medicine in Texas says that the immediate impact of the first day of DST is getting an hour less of sleep. In theory, the one-hour time change shouldn’t affect our internal clock a lot, and we should be able to adapt after two to three days. However, more and more people report experiencing prolonged sleep disturbances during DST. It can happen for various reasons.

In order to understand how our sleep can be affected by daylight saving time, we should understand how our circadian rhythm works. Our body’s inner clock regulates a number of physiological functions except sleep. It is responsible for hormone release, metabolism, and managing fatigue and alertness. During the transition on or off daylight saving time, our inner click is a bit off. Since the master body clock regulates more than physiological functions, we feel like we are entirely out of sync. During the transition to DST people often feel irritable, fatigued, hungry, or even depressed.

The best thing you can do to prevent this is to make adjustments a few days before DST or immediately. It is crucial to eat and sleep according to the new time. Although this is common sense, it may be quite tricky because our body tells us to do otherwise. Adults usually don’t have problems adjusting to DST. However, the change may be problematic for teenagers and all people with sensitive circadian rhythms. Every person functions in a unique way, and there are a lot of variations in terms how will our body respond to this sudden change.

DST Has Similar Effects as Time-Zone Switching

Transitioning on or off DST is very similar to switching time zone during travel. Shifting to an earlier time is like flying eastward, and our body adapts to it harder. Shifting to an hour later is similar to flying westward, and it’s much easier for our bodies to adjust. Everyone feels better when they have an extra hour of sleep.

How Springing Forward Affects Our Health

DST doesn’t jeopardize our health or affect it negatively in a severe manner. However, since it seems like we are forcefully pulled from our beds an hour earlier, it severely affects our mood. Apart from mood changes, disruption of circadian rhythms and sleep loss can lead to poor cognitive functioning. Due to poor cognitive functioning, we are more prone to car accidents, work injuries and similar.

Why Do We Still Have DST?

Don’t you think it’s nice to leave work at 5 pm and still have several hours of daylight to enjoy? DST cannot be the standard all year long, because, during winter, we would get up and go to work when it’s still dark. Going to work during dark may have safety implications. On the other side, extra daylight in the evening may lead to less crime.

The idea of daylight saving time emerged during war years and was established by law in 1918. It was repealed in 1919 and re-established during World War II from 1942 to 1945. In 1966, the Uniform Time Act provided standardization for the beginning and ending dates of DST in the US. The law allowed some local exceptions. Due to those exceptions, two states, Hawaii and Arizona, don’t recognize daylight saving time. Some countries such as California consider doing the same.

The fact that DST begins on a Sunday means that people have a full day to adjust to the new time before returning to work or school on Monday. Dr. Earnest advises us to take advantage of that. Another tip is to gradually shift your time and adjust to the new time by getting up half an hour earlier that you are used to. Doing this two days before DST should be sufficient.

Reasons to Get More Sleep

Have you ever considered how essential sleep is? Moreover, have you ever thought about how adding just one more hour of sleep each night could change your life? Experts in sleep science suggest that an … Read more

Written by:

Derek

Last Updated: Sun, February 23, 2025

Have you ever considered how essential sleep is? Moreover, have you ever thought about how adding just one more hour of sleep each night could change your life? Experts in sleep science suggest that an additional hour of sleep nightly can have a substantial impact on your health. Studies show a fine line exists between getting enough sleep and not getting enough, with the former being vital for good health and the latter risking it. Lack of sleep can significantly affect various aspects of your physical and mental well-being, including your mood, weight, and even your sexual health. If you’ve been sleeping less than the suggested 8 hours per night recently, think about some strong incentives to go to bed earlier tonight.

Better Health

Sleeping 8 hours per night will not grant you immunity for illness. However, studies suggest that insufficient sleep can increase risks of some serious diseases and medical conditions such as heart disease, heart attack, diabetes, and obesity. Typically, a person can feel these consequences only after years of sleep loss. However, when it comes to diabetes, you have to be extra careful. A recent study simulated the effects of disturbed sleep of shift workers on ten young healthy adults. After just four days, their glucose levels have significantly increased, to a degree that it is qualified as pre-diabetic.

Better Sex Life

According to a poll we have recently conducted, around 30% of people believe their sex life is negatively affected by lack of sleep, simply because they are too tired. Some studies suggest that lack of sleep lowers the testosterone levels in men. Of course, not getting having enough time for snoozing can affect your love life in a less direct way too.

Alleviate Pain

If you suffer from chronic pain, or you have suffered a recent injury, visiting the dreamland may help you alleviate pain. Some studies have shown that during sleep, our body restores and even lowers pain. It basically serves as a natural supplement medication for pain. However, it may be hard to fall asleep when you are in pain.

Lower Risk of Injury

Sleeping 8 hours a day will keep you safer. How? Because sleep deprivation is linked with some of the most notorious disasters in the history, such as the destruction of the space shuttle Challenger. Unfortunately, one out of five car accidents in the US is caused by drowsy driving. The fact is that if you are sleepy, you will be prone to any kind of accident because you are less focused and alert. So, when you are tired, even the simplest activities such as chopping vegetables can result in injuring yourself.

Better Mood

Getting enough shuteye doesn’t mean you will always be happy, but as you have certainly noticed, lack of slumber will most likely make you fell groggy and cranky during the entire day. Failing to meet the sandman regularly also affects you emotional regulation. So, when you are tired or exhausted, you will more likely burst into tears, laugh uncontrollably, or yell at somebody.

Better Weight Control

Sleeping 7 to 9 hours a day can actually help you regulate your weight. On the contrary, sleep loss can result in weight gain. Why does this happen? The problem is part hormonal, part behavioral. Lack of sleep causes hormonal misbalance which may slow down your metabolism or cause you to feel hungrier than usual. The hormone leptin is responsible for this. Leptin is a hormone that signals your brain when you are full. When you don’t sleep as much as you should, levels of leptin drop, which may cause night craving for food or specifically for high-fat and high-calorie foods. When it comes to behavior, when you are tired, you are less likely to go for a jog or cook a healthy dinner after work.

Clearer Thinking

When you are tired and exhausted, you will fell fuzzy during the entire day, and it will seem that your brain just can’t get out of its first gear. That is because sleep loss affects your cognition, attention, and even decision-making. If you have started doing strange things such as leaving your keys in the fridge and similar odd mistakes, you should definitely get more sleep.

Better Memory

As lack of sleep can affect our cognitive abilities, it can also affect our memory. Lack of shuteye can lead to forgetfulness, especially of recent events. Studies have shown that sleep loss makes hard for our brain to process and consolidate memories from the day. The fact is that without enough blissful slumber, your memories can’t be stored correctly, so they will eventually be completely lost. As this isn’t enough, some researchers claim that lack of sleep increases the chances of developing false memories.

Stronger Immunity

Did you know that sleep can protect you from the common cold? In a recent study, scientists have monitored sleep habits of over 150 people for two weeks. After two weeks, they exposed them to a cold virus, and the results showed that people who got seven or more hours of sleep per night are three times less likely to get sick than people who sleep less than seven hours a day. Of course, this study is inconclusive because there are a lot of other factors that may have affected the immunity of the examinees. However, you can’t go wrong if you decide to sleep 8 hours every night.

REM Sleep: Definition, Functions, Disorders, Research

Written by:

Dusan

Last Updated: Tue, February 11, 2025

Medically reviewed by:

Carlos Del Rio-Bermudez

Carlos is a neuroscientist and a medical & science writer with more than eight years of research experience in the field of Neuroscience. Prior to working full time as a medical writer, he was a postdoctoral researcher at the University Hospital of Bern (Switzerland). Carlos obtained his PhD from the University of Iowa (USA), supported by the Fulbright Program.

Some of the areas Carlos focuses on are RNA therapeutics, Rare Diseases, and REMS/RMPs. He has authored multiple original research papers in top journals in the field, book chapters, and periodicals. Carlos has also participated in international scientific meetings; most notably, he was invited to present his dissertation research at the 2018 Gordon Research Conference on Sleep Regulation and Function.

Sleep is one of those things where the beautiful complexity of our brains come to full shine. There are a lot of things we don’t understand about sleep, but it is clear to everyone that it is a biological necessity.

We need sleep to recover both mentally and physically, integrate memories, learn, stay focused, process emotions, among others. And the more scientists learn about how our nightly rest affects other aspects of our lives, the more they attempt to elucidate some of its mysteries.

That’s how researchers ended up characterizing the sleep cycle and learning about the different sleep stages. In clinical settings, we differentiate light, deep, and REM sleep stages based primarily on different patterns of brain activity, but also in relation to heart rate variability, breathing patterns, and muscle activation.

REM sleep (also called paradoxical sleep, or active sleep) has been the subject of intensive research and discussions since it was first described in the early 50s. The fact that most of our dreaming activity occurs during this sleep stage has also created a mysterious aura around REM in popular culture.

The research on REM sleep is extensive, and it has been going on for more than 65 years. If you are looking to learn more about REM sleep and related phenomena, this article has all the answers.

What Is REM Sleep?

Sleep wasn’t that exciting among researchers before the 20th century. Until then, sleep was thought to be an inactive state when our brain shuts down due to a lack of response to external stimuli. This understanding of sleep as a passive state made the topic unattractive to most researchers, and it wasn’t until the discovery of REM sleep that they began to pick an increased interest.

In 1953, a team of researchers from the University of Chicago noticed periods of ‘active’ sleep with regular, rapid eye movements (or REMs).[1] It looked like these active sleep periods alternated with periods of quiescent sleep. A few years later, they showed that this state correlates with specific brainwave patterns and dreaming. [2.3]

Besides rapid eye movements, we now know that REM sleep is also characterized by the increased frequency and decreased amplitude of cortical EEG, high-amplitude theta waves in the hippocampal region, muscle twitches, inactivation of skeletal muscles, body temperature fluctuations, autonomic respiratory activation, and increased arousal threshold.[4] Since the EEG readings resemble that of a waking state, but the muscles are shut off, some scientists refer to this state as ‘paradoxical’ sleep. [5,6]

REM sleep is not exclusive to humans. Studies found that most mammals, birds, reptiles, and surprisingly some invertebrates like cuttlefish could experience REM or REM-like sleep.[7,8,9,10] And even though it was first believed that REM is connected to homeothermy (i.e., the ability to keep a stable internal temperature) since it was only observed in mammals and birds, recent research clearly showed that some reptiles exhibit some key features of REM, including rapid eye movements. That means that the origin and evolution of REM sleep probably go way back before the era of birds and mammals, and could be present in all amniotes. Although these animal groups share a common ancestor, the duration and characteristics of the different sleep stages are quite different between species, suggesting that sleep has been shaped by ecology and evolution [11] For instance, sleeping mice experience REM sleep every 10-15 minutes, while in humans, it occurs every 90-120 minutes.[12.13] And the duration varies across species as well; while we spend around 25% of total sleep time in the REM phase, giraffes, for instance, spend less than 5%. [14]

How Do We Measure REM Sleep?

REM sleep can be accurately detected and analyzed in a controlled environment, like a lab or sleep center. In a sleep study, subjects are attached to a series of electrodes and other medical devices that measure different attributes related to sleep, namely:

Electroencephalogram (EEG) measures the electrical activity of the brain. That is important as the brain produces different brainwave patterns across the sleep-wake cycle. When we are in REM sleep, our EEG waves exhibit fast frequency and low amplitude, thus resembling those we observe during wakefulness. During stage 3 of non-REM sleep (also called slow-wave sleep), EEG waves show low frequencies and high amplitudes.
Electromyography (EMG) measures muscle tone and activity. This parameter also differs between sleep and wakefulness, and REM is characterized by muscle atonia (that is, lack of muscle tone) and myoclonic twitches.
Electro-oculography (EOG) is a measurement of the eyes’ electrical activity, which increases with the eye movements characteristic of REM sleep. These movements can easily be spotted in humans, but they may not be as distinct in other species.

Body temperature, respiration, and arousal threshold can also be measured in these controlled conditions. This whole process of measuring sleep is called polysomnography and is usually performed to detect the cause of sleep problems in people struggling to get enough rest.

Sleep studies on animals include similar measurements and are mostly performed in rodents and other species in captivity.

How Does the Central Nervous System Control REM Sleep?

Animal studies have provided interesting insights into the mechanisms that originate and sustain REM.

The brainstem is a part of our central nervous system (CNS) responsible for some of the primary physiological functions like breathing, heartbeat, swallowing, blood pressure, and sleep and arousal. Because of that, it was a natural candidate to inspect and find out whether it has any control over some of the components of REM sleep.

The early studies on cats identified part of the brainstem called the pons to be responsible for muscle atonia during REM sleep.[15] Researchers found that lesions in this region caused animals to exhibit overt motor behavior during REM since their skeletal muscle activity was disinhibited. Later studies located the exact pontic region responsible for this, the so-called sublaterodorsal tegmental nucleus (SLD). [16]

SLD and caudal laterodorsal tegmental (cLDT) neurons produce glutamate, which is a common excitatory CNS neurotransmitter. They are mostly active prior to and during REM sleep, and by activating inhibitory interneurons in the ventral medulla and spinal cord, they produce muscle atonia.[17] Disrupting the activity of these neurons leads to REM without atonia. [18,19] On the other hand, several studies have shown that manipulating different neuronal subgroups in these brainstem structures can affect other aspects of REM sleep, including REM quantity and cortical activation.

We also know that neurons in the lateral hypothalamus that secrete melanin-concentrating hormone (MCH) are particularly active during REM sleep.[22] They could possibly promote REM by inhibiting neurons in other midbrain and brainstem regions. Neurons in supramammillary hypothalamus are also essential for REM sleep control and theta wave activity, additionally highlighting the complexity of network circuits in REM regulation.[23] In summary, brainstem, midbrain, and hypothalamus remain the most crucial brain parts when it comes to REM sleep.

The Genetics of REM

Do genes play any role in the regulation of REM sleep? Although this is not an easy question to answer, scientists have made substantial efforts to understand the genetics of REM sleep

A 2015 study investigated receptor coding genes for one of the most abundant neurotransmitters – acetylcholine.[24] This neurotransmitter is essential for neural signaling, and increased levels during sleep are detected in the cortex and hippocampus. Chrm1 and Chrm3 are two of the five acetylcholine receptors suspected to play a role in REM sleep. Using genetic tools, researchers silenced the genes coding for these receptors in mice and then observed the effects it had on sleep. Interestingly, this silencing led to a massive decrease in REM and non-REM sleep. Mice lacking Chrm1 showed fragmented and shorter REM, while Chrm3 inactivation also affected non-REM sleep. When both genes were shut off, it led to almost complete elimination of REM.

These findings illustrate how genetic tools can give us exciting insights into REM sleep. Understanding how genes regulate sleep could help us better understand how our bodies generate sleep and the etiology of sleep disorders.

The Functions of REM Sleep

We know sleep is essential for proper functioning, but can we say the same about the REM phase? Would anything change if REM sleep didn’t occur, or is it crucial for us as any other part of the sleep cycle?

It turns out that REM is vital for many aspects of our lives. Therefore, we split this section into a few different categories to organize all the interesting details you need to know about the functions of REM sleep.

The Ontogenetic Hypothesis

Early studies concluded that newborns sleep way more than adults, and that showed to be the case for both humans and other mammals. Interestingly, the relative amount of REM and non-REM sleep in early development is also different from adults. The graph below depicts how the relative time spent on REM sleep changes across the lifespan in humans.

Source: Roffwarg, HP, Muzio, JN, Dement, WC. (1966). Ontogenetic development of the Human Sleep Dream Cycle. Science

Newborns snooze for 16 hours a day, and they spend around 50% of that time in REM. This percentage decreases with age, and adults spend less than 25% of their time asleep in REM. So, why is this happening?

A 1966 article published in the journal Science proposed an explanation for this relative increased REM in the early stages of development.[25] It turns out that neural activity is essential for the rapid growth of the nervous system. The authors argued that, since babies spend most of their time sleeping, they don’t receive enough external stimulation to keep their brains active. Remember that REM is also called “active sleep”? Indeed, during REM sleep, the eyes move rapidly, muscle twitches are seen throughout the body, neural circuits get activated… and all this activity supports the development and shape the young body and mind. Thus, according to this “ontogenetic hypothesis,” REM sleep provides necessary activity for brain circuits to develop. This notion would also explain why the proportion of REM sleep decreases with age. As infants get older, they have more and more opportunities to interact with the outside world and receive lots of stimulation during wakefulness.

Similarly, it seems that the abundant muscle twitches that babies experience during REM sleep can stimulate sensorimotor development in the early stages of life. If you are wondering how we go from crude limb movements in infancy to fine motor control in adulthood, be aware that twitching during REM may play a significant role there. Scientists have found out that sleep twitches evoke sensory responses in the newborn brain, and thus stimulate neurons throughout the nervous system. Because babies spend a lot of time in REM sleep, and because twitches are so abundant during this sleep stage, scientists also believe that they contribute to the wiring of new neuronal connections in the sensorimotor system.[26] Additionally, myoclonic twitches during active sleep have been shown to trigger and synchronize neural oscillations across brain areas, potentially contributing to synapse formation, neural differentiation and migration, and neural connectivity. [27]

Another REM function important for development is the strengthening and maintenance of newly formed connections between neurons, or synapses.[28] A key feature of neural development is the formation of abundant, excess synapses; however, only a small number of those will be maintained through life. The removal of these excess connections is called “synaptic pruning,” and it was recently shown in young mice that REM sleep deprivation disrupts this process.

Memory and Learning

That last segment already hinted at how REM sleep could be responsible for our ability to store memories and learn new things. Synaptic pruning and strengthening is not only essential during development, but it is also needed for learning. Synaptic connections are vital for memory forming, but only a small portion of newly formed circuits are maintained. Essentially, the brain chooses which circuits to keep, and it incorporates them into a vast neural network of existing knowledge and memories. Over 75% of new synapses get pruned right away while the rest are kept, which could lead to the formation and incorporation of new memories. [30] And again, it looks like active sleep is when all of this happens.

In 2016, scientists managed to highlight neural oscillations during REM sleep responsible for memory consolidation. [59] They showed that silencing specific neurons during REM phase impaired newly obtained contextual memory, while doing it at any other point had no such effect.

However, remember that not all memories are the same. Memorizing random facts activates different brain centers than learning how to ride a bicycle, or remembering a highly emotional event in your life. It seems that REM sleep doesn’t play the same role in every type of learning, and its role in memory consolidation is still controversial. However, REM sleep can “rescue” memories after they have been heavily damaged by interference, which typically occurs when other memories prevent retrieval of certain information. [32]

Studies in both humans and animals show that REM sleep plays a significant part in procedural, spatial, and emotional memory.[33,34,35,36] Although there are inconsistencies across studies, this suggests that REM may not be involved in the consolidation of declarative memories (remembering random facts), which is thought to be supported by slow-wave sleep. Many of the studies showcasing the benefits of REM on memory and learning showed that post-learning REM boosts performance in cognitive tasks. Typically, control groups stayed awake or slept after the learning process, but were prevented from entering REM sleep. While the conclusions of these studies are valid, researchers failed to see such a link in many other experiments. [37,38]

One of the biggest arguments against the role of active sleep in memory consolidation is that the techniques used to suppress it often causes a certain amount of stress, and the learning impairment could be the result of that.[39] There have been reports of patients with lesions in the pontic area, which is essential for REM generation, and these individuals didn’t experience paradoxical sleep. It is interesting that these patients led normal lives and had no problem with memory consolidation.[40]

To make things a bit more complicated, another study where researchers investigated a link between active sleep and memory retention showed interesting results. Pharmacologically induced REM suppression didn’t impair skill learning; in fact, it enhanced it.[41] The results of these studies are sufficient to make us question the true nature of REM sleep. More studies are needed to draw any firm conclusions.

Physiological Roles of REM Sleep

Some scientists concentrate on the physiological functions of REM sleep. For instance, according to the energy relocation hypothesis, organisms evolved three different strategies to maximize the efficiency of energy usage. One of them includes sleep-wake rhythms, where animals would experience periods of rest associated with less expenditure of energy so the organism can focus on other biological processes compared to wakefulness. [42]

It’s not that sleeping saves energy for when we are awake, it’s that it is spent differently. For instance, when awake, animals need to mate and find food, shelter, and other resources, which limits their ability to perform different functions like the growth of neurons, myelin formation, and other brain functions. This is where sleep comes in! As for REM sleep specifically, suppression of both thermoregulation and muscle tone saves a lot of energy, which can then be used to maintain sleep-dependent CNS physiological functions.

This hypothesis makes perfect sense when we are talking about endothermic or “warm-blooded” organisms, like birds and mammals. These animals are able to control their optimal body temperature via internal means. Because this internal regulation of temperature consumes a lot of energy and is specifically suppressed during REM sleep, the energy allocation hypothesis argues that REM has evolved to, so to speak, give the body a break so it can focus on other biological needs. However, with the discovery that reptiles and possibly other animals could be able to experience REM sleep, we are not sure where that would fit in the energy relocation hypothesis.

A 2019 study showed that sleeping mice who experienced warm ambient temperature within their thermoneutral zone (i.e., the range of ambient temperature where the body can maintain its internal temperature without needing to use more energy than the basal rate) increased their REM sleep duration, as compared with mice who in the cool or constant baseline ambient temperature conditions.[43] These findings support the energy allocation hypothesis, as mice opportunistically expressed more REM sleep in the warmer environment, where they didn’t have to spend that much energy in regulating their internal temperature

REM sleep also affects hormone production and metabolism. For example, REM sleep deprivation disrupts leptin homeostasis, which is a hormone that plays a massive role in modulating appetite. That could be one of the reasons why many studies found a link between lack of REM and sleep in general, and weight gains, and obesity. [45]

REM Sleep Disorders

Studies of abnormal REM sleep control primarily focuses on identifying neural circuit mechanisms leading to these disorders. Interestingly, narcolepsy and REM sleep behavior disorder show many similarities in the deterioration of mechanisms leading to healthy REM sleep.

REM Sleep Behavior Disorder

Rem Sleep Behavior Disorder (RBD) is a neurological condition where patients lose their ability to suppress muscle tone during active sleep. [46] Symptoms vary from exaggerated muscle twitching to shouting, sudden violent movements of limbs, to complex behaviors where people look like they are trying to reenact their dreams.[47] Although it may not seem like a lot, individuals with RBD can injure themselves or their partner during sleep.

But the most worrying thing about RBD is that the majority of patients develop a neurological condition 6-15 years after the onset of RBD symptoms.[49] Most people develop Parkinson’s disease, multiple system atrophy, dementia with Lewy bodies, and other synucleinopathies due to neurodegeneration.[50] This link indicates that RBD manifests due to neurodegeneration, and the new evidence points out to deterioration of neurons in the brainstem, precisely dorsal pons. [51]

Considering that we already found these centers to be responsible for producing REM atonia and playing an active role in other parameters of paradoxical sleep, it is clear why degeneration of these areas leads to RBD. But, since so many people with RBD develop a synucleinopathy, scientists pose a question whether it can be considered as a separate disorder, or whether we should treat it as one of the symptoms that preclude neurodegenerative diseases. One study found that over 80% of patients with RBD developed a neurological condition, and the survival rates 14 years after the initial diagnosis were only 7.5%. [52]

Synucleinopathies are named after a misfolded protein called alpha-synuclein, which causes the degeneration of neurons. According to Parkinson’s disease pathobiology, this protein originates in the gut and then slowly progresses around the body, eventually affecting the brain. [53] Once they reach the brain, the brainstem is the first place of contact, close to REM circuits. Afterward, it spreads to the other brain structures, causing motor and cognitive impairments that characterize Parkinson’s disease. [54]

Interestingly, while brainstem is an area where many vital functions like breathing, chewing, and swallowing originate, they are unaffected by alpha-synuclein degeneration in RBD. Understanding why these circuits remain untouched while REM ones are widely affected is important for future understanding of these conditions, and possible prevention of RBD.

Narcolepsy

Narcolepsy is a sleep disorder estimated to affect 1 in 2000 people. [55] It is mostly caused by the lack of neurons that produce orexin in the lateral hypothalamus.[56] This neuropeptide plays an essential role in controlling sleep, wakefulness, and appetite. The most common symptoms include excessive daytime sleepiness, fatigue, irresistible sleep attacks, sleep paralysis with vivid hallucinations, and cataplexy.[57] Cataplexy is described as sudden and transient muscle weakness and loss of muscle tone during conscious wakefulness.

Cataplexy resembles muscle atonia of REM sleep, which is why scientists believe that the same neural circuits are responsible for both. And there seems to be more and more evidence supporting this hypothesis. For instance, certain antidepressants used to suppress cataplexy, also affect REM sleep.[58.59] There is rebound in REM and cataplexy after the withdrawal of medications, pointing to a closely related neural regulation of these events.

Cataplexy is usually triggered by strong emotions like fear, surprise, and laughter. Amygdala is a brain structure involved in processing emotions, and recent studies show it is also active during both active sleep and cataplexy. [61,62]

We already mentioned that RBD precludes a variety of neurological disorders. In addition, it looks like RBD and narcolepsy are closely related, as one study showed that over 50% of narcolepsy patients also experienced RBD.[63] What’s even worse is that many patients who take antidepressants to ease narcolepsy symptoms can also face an increase in REM phase movements, even if they don’t fully develop RBD.

You get the idea of how sudden irresistible cataplexy events in narcoleptic patients can impair even the easiest daily activities. Cooking a meal can turn into a disaster, and narcolepsy patients need to be extremely careful when driving, as you don’t want to be behind the wheel when cataplexy strikes. That is why it is essential for people experiencing narcolepsy symptoms to talk to their doctor immediately. They can run tests, find out what is really causing their sleep problems, and provide advice on how to move forward.

The Fascinating World of Dreams

Dreams have captivated us since the dawn of time. From ancient people believing these nightly visions showed the future, artists who claimed their inspiration came to them in sleep, philosophers trying to find the meaning behind dreams, to psychologists considering them to be the door to our unconscious mind, and trying to find out what is really going on behind all of this along with other scientists. However, dreaming remains a mystery to this day.

Dreams can occur during different sleep stages but are most closely associated with paradoxical sleep. Many scientists have given their view on why dreams occur. However, we need more research to draw solid conclusions. Any of the proposed hypotheses could be valid, and they are not even mutually exclusive, as dreaming may serve different functions.

By the continuity hypothesis, your dreaming state reflects conscious experiences and is widely affected by them.[64] So, the content of your dreams is impacted by waking life, emotional involvement, personality traits, and the time of the night when dreams occur. A 2018 study found that people with symptoms of depression and anxiety experienced more dreams with negative and harmful connotations.[65] These findings support the hypothesis that waking life plays a major impact on what goes on in our heads during the nightly slumber.

Some have proposed that dreams help us consolidate memories by playing over events from our life. However, we all know that these events often don’t make too much sense, and while many of us would probably love to be able to fly or teleport like in dreams, it is not very likely. But these nightly visions could help us process emotions, or encounter situations that would make it easier to face them in real life. [44]

Since recollecting dreams is not so easy, scientists are trying to visualize them by tracking brain activity in dreaming subjects. However, it is not an easy task since there is not a one-to-one correlation between activity patterns and dream content; furthermore, even the same dream wouldn’t have the same pattern of brain activity in different people. One study used machine learning models to predict the content of dreams, and it was actually successful.[66] That gives us hope that decoding what goes on in our head during sleep is not such an impossible task.

However, some speculate that dreams may not have to serve any particular purpose and that they are simply a byproduct of our brain activity during sleep. Since neurons fire quite a lot during sleep, dreams could be just a random manifestation of that. Unfortunately, that takes away from the mystery and intrigue surrounding sleep. One thing is sure, we won’t stop being fascinated by dreams, and scientists are trying their best to understand them a little better.

Interesting Facts about REM Sleep

Some random facts about active sleep can paint a good picture of how fascinating this state is. So, let’s look at some of them:

Eye movements during REM correlate with visual experiences during sleep. One study found that they mirror the scanning of scenes in our dreams.[67] It looks like they may not be random at all, but indicate that you are looking at many different visual stimuli happening in your slumber.[68]
Even blind people dream. And weirdly, their eyes also move during REM, even though they have impaired visual dreams, but rely more on other senses. [60]
REM sleep can improve creative thinking and problem-solving. A 2009 study shows that REM enhances the integration of random information and creative problem solving, making “sleep on it” a great piece of advice.[69]
Some people claim to be able to control the content of their REM dreams. This phenomenon is called lucid dreaming, and some claim that you can train yourself to recognize that you are dreaming, and then gain control of the events, narrative, environment, and other aspects of the dream.
Lack of sleep is linked to an increased risk of obesity, and it looks like the REM phase is particularly important. One study found that compared with normal-weight children, overweight children showed reduced sleep efficiency, lower REM activity and density, and it took them longer to reach the first REM period. [70]
Alcohol and REM don’t mix. Although many people believe consuming an alcoholic beverage could help them sleep better, this is entirely untrue. In fact, drinking leads to poorer sleep and fragmentation. And research even shows that alcohol consumption increases the likelihood of developing RBD.[71]
The same goes for recreational drugs, as studies found a worsening effect on REM sleep quality.[72]
Interestingly, after facing sleep deprivation, the architecture of sleep changes. Selective disruption of REM leads to REM sleep rebound or prolonged periods of REM sleep.[73]
Amazingly, 87% of patients experiencing RBD are reported to be male.[74] Investigating why the condition is not as prevalent in women could give us useful info on how to battle RBD.

Where Is REM Sleep Research at the Moment?

Even though the fascination with dreams has been going on for a long time, sleep science is a relatively new field. In the last few decades, we have learned a lot about what happens during sleep and how it impacts our brain and body. However, a lot of things remain a mystery. So, let’s take a look at what is happening with REM sleep research at the moment.

A new study from the Current Biology journal links restful REM sleep with processing distressing emotions.[75] Unpleasant emotions trigger activation of the amygdala, which acts as a siren, telling us that something is wrong. In their experiment, they showed that restful paradoxical sleep helps to shut off that alarm and not be bothered as much the next time we encounter that distressing event. Impairment of the REM phase meant that the amygdala stayed active even after sleep, highlighting the role of this stage on stress adaptation.
Ever wonder how we forget things? Well, a new study from Hokkaido University may give us some insight.[76] It looks like REM sleep plays an essential role in our ability to discard information. Remembering everything we encounter is simply not possible, which is why the brain must decide what’s important, and what it can eliminate. It looks like neurons producing melanin-concentrating hormone are responsible for the active forgetting of unnecessary memories. When researchers turned off these neurons during REM, mice performed better on memory tests. In contrast, when the neurons were selectively activated, mice performed worse.
Zebrafish is a standard model in many scientific experiments, and now it can give us a better insight into the origin of REM. With current findings of active sleep in mammals, birds, and reptiles, it seemed like it could be a state exclusive for these groups of animals called amniotes. But new research shows that zebrafish could experience a state that resembles REM sleep as well.[77] That would push the evolution of this phase a lot back, and it is possible that it evolved underwater. With such a long history, it is clear that REM plays an essential role, even though we may not be entirely sure about what it is. Genetically engineered zebrafish used in this experiment produced a fluorescent molecule that lights up when neurons and muscles are active. This cool video shows what the electrical activity looks like during REM sleep.
A study published in Nature Communications identified neurons responsible for eye movements (EM) during REM.[78] These findings could help us better understand the role of EM, and whether they are a byproduct of this phase or they serve a specific purpose.
New evidence suggests that neurons in neocortex and hippocampus fire at different rates during REM and non-REM sleep.[79] While non-REM is characterized by homogenization of neural activity, firing during REM is a lot more diverse and chaotic, just like dreaming during this stage. These findings offer some mechanistic insights into the complementary roles of these two sleep stages.

As you can see, research in this field is very active, and while there are a lot of questions we need to answer when it comes to REM sleep, scientists are doing their best to uncover all the mysteries of this phase, and sleep in general.