What is REM sleep and why is it so important?

Remember all the times you’ve woken up after having the strangest dream, and could swear it was real? Whilst dreams themselves—which seem to be linked to our thoughts and memories—are still a mystery, we do have a pretty good understanding about how and when they occur during our sleep cycle. REM sleep, or rapid eye movement, is one of the five stages of sleep, and is characterised by stimulated brain activity, increased heart rate and blood pressure — and what we call dreams.

Uncovering the Mysteries of REM Sleep

We’ve still got a long way to go before truly grasping the inner-workings of this wondrous organ called the brain, but that doesn’t stop its elusive mysteries from being a perfectly normal and welcome part of our lives. While scientists are conducting exciting and mind-boggling research in a lab somewhere, we certainly don’t spend much time questioning our ability to have bizarre dreams at night, or being able to remember things that happened to us many years ago. However, it would seem that there is a connection between our ability to learn, create memories, and dream at night — which occurs during REM sleep.

So what does REM sleep mean, and why is it so important to us? Well, for one, can you imagine a life without dreaming? Seems a bit bland, doesn’t it? Apart from being exciting, bizarre, lovely, magical, scary, and outright senseless, dreams actually seem to serve a purpose in the healthy function of our brains and bodies. During REM sleep, rapid eye movement occurs as the brain becomes energised and bursts with activity. As we experience whatever imagined scenario may be playing out in our heads, our eyes are darting in all directions, with electrical activity firing across many regions of the brain — including its vision centre. Not only are electrical signals amplified during REM, but our bodies produce certain proteins that seem to play a role in cell regeneration. It is believed that all of this stimulation revitalises the brain and body, and allows us to handle daytime function, make new memories, and experience life with refreshed focus.

The Stages of Sleep

As we sleep, our brains go through a cycle of five distinct stages. The entire cycle lasts about 90 minutes, and repeats four to six times during a full night’s rest. The first four stages are NREM sleep (non-rapid eye movement), while the fifth and final stage is the only REM stage.

Stage 1: The first stage of sleep is known as the transitional phase. When we lay down for sleep, we find ourselves drifting somewhere in between sleep and consciousness. During this stage, we feel very drowsy, and experience involuntary muscle jerking and the occasional falling sensation which are referred to as hypnic myclonia. This sometimes causes us to have a bit of a start and suddenly wake up. If you remember this happening, maybe you’ll remember that you could feel yourself drifting off to sleep when it occurred.

Stage 2: We spend as much as half of our time asleep in the second stage of sleep. This light stage of sleep is characterised by a decrease in heart rate and body temperature. During stage two, we experience slower brainwaves (neural oscillations of our central nervous system), with occasional brainwave bursts known as sleep spindles. At the same time, our bodies will go through cycles of muscle tone and relaxation.

Stage 3 & 4: The third and fourth stages of sleep are often grouped together as they are both stages of slow wave sleep (SWS). Slow wave sleep is characterised by slow brainwaves known as delta waves, with occasional interruptions by faster waves. During SWS, blood pressure and heart rate drops while breathing becomes deep and slow. This period of sleep is also known as deep sleep, because it can be difficult to wake someone up during this stage — and they may find themselves very disoriented if woken during deep sleep. The difference between these two stages is the number of delta waves we experience, with an increase in delta waves during stage four. Deep sleep stages seem to have a restorative effect on our bodies. During deep sleep, hormones are released that help revitalise muscle and organ tissue, as well as keep our appetite healthy the following day. Stage three and four are also characterised by increased blood flow to muscles — which brings oxygen, nutrients, and promotes healing.

Stage 5 — REM Sleep: Last but certainly not least, the final stage of sleeping is the REM cycle. REM sleep makes up about 20-25% of total sleep time in adult humans, while newborn infants can spend as much as 80% of their sleep time in the REM sleep cycle. It is believed that REM sleep is crucial to brain development early in life, which is probably why babies spend so much more time in the REM stage. Next time you hear someone say “sleep like a baby”, think plenty of dreams and reinvigorated brain cells!

During REM sleep, the body is immobile and in a sort of paralysed state as the mind bustles with activity. Blood pressure and heart rate both rise out of deep sleep levels, and breathing becomes more shallow and sometimes irregular. Our brainwaves become desynchronised and behave as though we are awake. After REM sleep, we begin to waken. But if we haven’t had enough rest, the cycle begins anew with stage one. Undisturbed and comfortable, a person should experience four-to-six sleep cycles during the night and wake up after their last REM cycle. This is why we often wake up during a dream, and may feel as though we have been dreaming all night.

Importance of REM Sleep

While we may not understand the exact nature of REM sleep and how dreams work, we can certainly appreciate its impact on our well-being. REM sleep seems to play a major role in everything from learning, remembering and cognitive performance to cell regeneration, being in a good mood, immune system function, and more. The production of proteins that occur during REM sleep are vital to our health, and according to studies, REM sleep deprivation can cause a weakened immune response and increased inflammation.

REM deprivation is also believed to increase pain perception as a result of stimuli in the central nervous system not being filtered normally (think of stubbing your toe a tad bit harder, and you get the idea). While dreams may not make a whole lot of sense at times, their purpose certainly does — when you consider the role they play in the health of your body and brain.

REM Sleep Behaviour Disorder

Healthy REM sleep involves paralysis of the body, during which we lie motionless as we go about in our imagination. However, a condition called REM sleep behaviour disorder (RBD) causes an impairment or absence of this paralysis, which prevents physical restraint and may cause us to “act out” our dreams during REM sleep. People with RBD may find themselves enacting their dreams by speaking, shouting, punching, kicking, jumping, grabbing, and other general movements. Symptoms of RBD range from harmless to violent and intense, and can be unsafe for a person while they are in an unconscious state.

The cause of RBD is not exactly known, but has been linked to withdrawal from alcohol, sedative-psychotic drugs (such as sleeping pills), and antidepressants (such as Prozac and Tofranil), as well as degenerative neurological conditions such as Parkinson’s disease and others.

How Do I Get More REM Sleep

Under normal conditions, a person should be able to get sufficient REM sleep with regular sleeping hours and about eight hours of sleep every night.

Practice healthy sleeping habits and get plenty of REM sleep with these tips:

• Get about 8 hours of sleep every night: A full night’s rest gives our bodies plenty of time to cycle through all five sleep stages a healthy number of times.
• Keep a cool environment while you sleep: Our body temperature decreases as we sleep, which is part of the natural sleep cycle. Keeping your body cool allows for a deeper sleep and healthy REM cycles.
• Avoid screens for at least an hour before bed: This means all phones, computers, TVs, etc. Electronic screens produce blue light, which disrupts and delays melatonin production in the brain. Melatonin is a natural hormone that regulates our sleep-wake cycle (circadian rhythm), and is produced at peak levels at night before bedtime. If your brain isn’t producing enough melatonin before bed, it will have a negative impact on the quality of sleep and the REM cycle.
• Take a hot bath before bed: According to sleep scientist Matthew Walker, a simple and effective way to prepare your body for sleep is to take a warm bath before bed. Taking a hot bath before bed causes your body to perform a “thermal dump”, where the skin’s blood vessels dilate and cause the body’s inner heat to radiate outward. Not only does this help you fall asleep faster, it allows you to sleep deeper throughout the night.
• Get more vitamin D: Vitamin D is the yang to melatonin’s ying. While melatonin is produced in our bodies during the night, vitamin D is produced during the day, and its deficiency can lead to poor quality sleep, insomnia, and an impaired immune system. Natural vitamin D production is always best (getting healthy sunlight before 10am or after 2 pm), while supplements are best taken in the morning (you shouldn’t take vitamin D at night or before bed, as it can keep you awake).
• Eat healthy: Healthy food choices and eating habits ensure that our bodies receive all the necessary nutrients and minerals to promote strong sleep.
• Exercise a little every day: Physical health is important not just for our quality of life but also for our quality of sleep. Take a few minutes out of your day and exercise to stimulate your cardiovascular and central nervous systems for better REM sleep.


Check out our article on How to Get to Sleep to learn more about quick sleeping techniques and how to sleep better tonight.