REM Sleep

REM Sleep is one of the three states of consciousness. Read on the learn what happens during this mysterious sleep stage and the questions that remain to be answered.

By Andrea Pisani Babich

Rapid Eye Movement (REM) sleep is one of the four stages of our sleep cycle and is easily recognized by its eponymous rapid eye movements from side to side under closed eyelids.

Other characteristics of REM sleep include:

  • quick and irregular breathing
  • increased heart rate
  • increased blood pressure
  • body temperature that reflects the temperature of your bedroom instead of decreasing as it does during the first three stages of sleep
  • brainwave activity similar to that while we are awake
  • sexual arousal in both men and women
  • twitching of the face and limbs
  • tendency towards obstructive sleep apnea due to lack of muscle tone within airways

But there is much more to know about REM sleep than just these descriptions. Our current knowledge of this stage of sleep is limited partly because it is a relatively new field of study and partly because of prevailing attitudes about sleep.

A Brief History of Sleep Research and REM Sleep

In 1924, a piece of technology called the electroencephalogram (EEG) was invented to study how the human brain functions during different activities and experiences, including sleep. By 1928, a man named Hans Berger was recording legible patterns of brainwave activity. But it wasn’t until 1953 that Dr. Eugene Aserinsky discovered rapid eye movements during sleep.

In the following five years, Dr. William Dement used the EEG to identify the sleep cycle and its four stages of sleep that are defined by changes in the brain’s electrical activity. Since then, researchers have learned a lot about the mysteries of sleep, primarily that sleep is not a time of total inactivity, a notion that even educated people clung to. This belief appears to have delayed the progression of sleep study. In fact, there is so much going on while we sleep, that for as many answers scientists have discovered, they have raised new questions including:

  • What is the function of sleep?
  • What is the exact role of each stage of sleep?
  • What is the function of dreams?
  • How does REM sleep influence memory formation?

Here is what we do know about REM Sleep.

Dreams and REM Sleep

Our dreams occur during this fourth stage of sleep, and they tend to be more vivid than the few dreams we may have earlier in our sleep cycles. Most dreams we remember occur during the longest REM sleep stage that happens just before we awaken, although dreams may occur throughout the night as many as seven times.

Dreaming is one of the many aspects of sleep that we still don’t understand. Scientists do not agree on the purpose of dreams, but there seems to be no shortage of theories.

Some theories about the role of dreams include:

  • Memory consolidation theory. Some scientists believe that our dreams bear some resemblance to events in our waking lives and that they help us to sort out important memories from unimportant ones. Those memories deemed important are processed into long-term memory.
  • Threat simulation theory. Subscribers to this theory think that our dreams provide us with opportunities to rehearse how to escape danger, injury, or death in threat scenarios. They suggest that dreams evolved as a way to help our primitive ancestors survive. Early humans who could avoid danger most effectively because they had prepared escape strategies in their dreams were more likely to survive than those who were unprepared. Dreams that prepared them for possible dangers and how to avoid them gave them an edge over their doomed peers who did not practice in the safety of their own minds.
  • Housekeeping theory. Francis Crick, who discovered the DNA helix, and Grahame Mitchison hypothesized that dreams act as an “unlearning” mechanism. According to this theory, dreams identify unwanted thoughts or erroneous information, and erase them from the brain lest they become the basis of obsession, paranoia, or other pathologies that prevent the brain from working efficiently.
  • Problem solving theory. Similar to the threat simulation theory, in this theory, dreamers act out scenarios or problems in their dreams and test out solutions that might be too threatening in their waking lives.
  • Multiple roles. There is no reason to believe that dreams serve only one of these purposes. Perhaps dreams fill all of these roles on an “as needed” basis.
  • No role. There are still some sleep experts who believe that, by and large, dreams are merely visual representations of random brain cell activity during sleep.

REM Sleep Behavior Disorder

Most characteristics of REM sleep are quite the opposite of the Slow Wave Sleep (SWS) stage that immediately precedes it. Unlike SWS or deep sleep, the physical and neurological events that occur during REM sleep are so similar to our waking selves, that REM sleep is also called paradoxical sleep. The paradox is that while our brains are intensely active and working as if we were awake, our bodies are almost completely immobilized to the point of paralysis. This loss of voluntary muscle movements, called atonia, appears to be a protection from acting out our dreams.

When this mechanism fails and people begin to move in response to what they are dreaming, they may be diagnosed with REM Sleep Behavior Disorder (RBD). This rare diagnosis is usually preceded by injury to themselves or their bed partners as a result of sleepers acting out their dreams, which are very vivid during REM sleep. Dreams that are violent or frightening could prompt the sleeper to scream, shout, punch, kick, or even jump out of bed and run from the room. Researchers have estimated that RBD affects only about .5% of the population, 90% of whom are male and over 50 years old.

People with REM sleep behavior disorder often later develop other neurological disorders including Parkinson’s disease, sudden dramatic drops in blood pressure, loss of smell, and cognitive impairment. Since REM sleep is regulated in the brainstem, the changes in this part of the brain that trigger these other neurological disorders also disrupt the normal muscle atonia of REM sleep.

Treatments for RBD include:

  • Clonazepam, which is effective in 90% of cases
  • Some antidepressants
  • Melatonin

REM Sleep and Depression

Research has shown that deprivation of REM sleep has no apparent effect on non-depressed people. While they compensate for their REM debt by having more of it when they are able to, there appear to be no long-term, adverse physical or psychological effects. All of which raises lots of questions about the function of REM Sleep. Do we need it or not? If so, why?

However, at least one sleep study of depressed people showed that skipping REM sleep, and therefore dreams, helped 9 of 12 of them to get past their depression in the five months of the study. Dr. Rosalind Cartwright, chair of psychology at Rush-Presbyterian-St. Luke’s Medical Center, told WebMD, “Depressed people don’t solve problems during their dreams, like other people do. They pile up their troubles, and the last dream of the night is the worst. They wake up in a worse mood if you let them sleep through those dreams. But if you interrupt them, they normalize and feel better in the morning.”

This was a small study and not everyone agrees with Cartwright’s findings. While some researchers see potential for further research in her conclusion, they note that the lift in mood is not long lasting and generally reverses after two or three days. But, certainly, Cartwright’s findings are tantalizing data points in the study of REM sleep and depression.


Plenty of research needs to be done in the field of sleep and its various stages. We’re here to help you get the best night’s sleep possible and live life to the fullest. Stay tuned to Mattress Advisor for the latest news in the study of sleep as it unfolds.


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