American Sleep Association

REM Sleep: Why is it important?

REM sleep is a stage of sleep that is characterized by low muscle tone, rapid eye movements and dreams. It is present in all mammals and has unique physiologic properties that distinguish it from non-REM sleep.

Key Points about REM sleep:

  • Associated with dreams
  • Rapid eye movements
  • Muscles are paralyzed

About REM Sleep

This stage of sleep is also known as 'paradoxical sleep,' or 'desynchronized sleep', due to the physiological similarities to a person’s waking states; which includes low-voltage, rapid, desynchronized brainwaves. It’s believed that the chemical and electrical activity that regulate this sleep phase originate in the brain stem, and this is most notably characterized by a combination of an abundance of acetylcholine (a neurotransmitter), and the almost complete absence of serotonin, histamine, and norepinephrine (monoamine neurotransmitters). (1)

What is REM Sleep

The punctuated REM sleep is immediately preceded by ponto-geniculo-occipital (PGO) waves, which are electrical bursts of activity originating from the brainstem. Approximately every six seconds during the transition from deep to paradoxical sleep, these waves occur in clusters and last for between one and two minutes. It’s when they move into the visual cortex that they exhibit their highest amplitude, thus causing the rapid eye movements in paradoxical sleep.

REM Sleep and Brain Energy

REM Sleep and Brain Energy In REM sleep, brain energy as measured by glucose and oxygen metabolism, equals or exceeds energy-use in waking. When compared to slow-wave deep sleep, both paradoxical and waking sleep involve higher use of acetylcholine (the neurotransmitter) which may well explain the faster brainwaves. Monoamine neurotransmitters serotonin, histamine, and norepinephrine are completely unavailable. (2)

It’s been discovered that injections of acetylcholinesterase inhibitor can induce paradoxical sleep in both humans and other animals already experiencing slow-wave sleep. This inhibitor effectively increases available acetylcholine. Carbachol has a similar influence, mimicking the effect of acetylcholine on neurons. The same injections in waking humans produce paradoxical sleep, but only when the monamine neurotransmitters are already depleted.

Gamma-Aminobutyric Acid (GABA) and Orexin are two other neurotransmitters that appear to promote wakefulness, decrease during deep sleep, and prevent paradoxical sleep. The brain’s chemical changes indicate continuing periodic oscillation, unlike the sudden changes in electrical patterns.

The Role of the Brain Stem in REM Sleep

During REM sleep, neural activity appears to originate in the brainstem, especially in the locus coeruleus and the pontine tegmentum.

As per the activation synthesis theory suggested by Allan Hobson and Robert McCarley in 1975-1977, controlling REM sleep involves REM-on and REM-off neuron pathways in the brainstem. REM-on neurons are mainly cholinergic, meaning that they involve acetylcholine; while REM-off neurons activate noradrenaline and serotonin, which, among other functions overpower the REM-on neurons. It was suggested by Hobson and McCarley that the REM-on neurons stimulate the REM-off neurons, thus becoming the mechanism for the cycling that occurs between REM and non-REM sleep. Lotka-Volterra equations were used to explain this cyclical inverse relationship. (3)

In 1981, Michael Jouvet and Kayuza Sakai proposed a similar model. It appears that during both wakefulness and REM, acetylcholine manifests in the cortex equally; but during REM it appears in higher concentrations in the brain stem.

Withdrawing GABA and Orexin may explain the absence of the other excitatory neurotransmitters. Positron emission tomography was used in research in the 1990s and confirmed the role of the brain stem. This research also suggested that the paralimbic and limbic systems within the forebrain, which are generally connected with emotion, showed greater activation than other areas.

Why is REM Sleep Important

REM sleep, or Rapid Eye Movement Sleep is one of the stages of sleep. It is the stage of sleep most associated with dreaming. During REM sleep the brain and body act very different than they do during other stages of sleep. During this stage of sleep the skeletal muscles act as if they are paralyzed. In fact all voluntary muscles, except for eye muscles are atonic, or without movement. This probably had some evolutionary benefit as it protected us and others from injury, as we would otherwise act out our dreams. (4)Why is REM Sleep Important

During REM sleep, the brain is more active than during other stages of sleep. The EEG, or electroencephalogram, resembles wake time. Of course, the eyes show a distinct pattern on the sleep study which demonstrates quick eye movements, hence the name. The skeletal muscles sometime show brief twitches which may be in phase with the eye movements.

What are dreams and Why do we dream? This is not easily answered. There are several theories about the significance of dream.  One belief is that dreams are the brains way of processing and storing pieces of information relevant to previous events.

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7 comments on “REM Sleep: Why is it important?”

  1. I've got sleep apnea and I sleep perfectly fine with with regular breathing until I begin dreaming have apnea and then wake up. I wake up every 90 minutes and would be a lot better off if I did not have REM sleep. There is quite a lot in this article but it does not have much to say about the importance of Rem Sleep despite posing the question.

  2. No. REM sleep is not important and is actually harmful in my opinion. All my patients who have morning headache, morning palpitation and/or hypertension all have “vivid dreams”. Some always experienced significantly elevated blood pressure and heart rates the moment when they woke up. And they all experienced “heavy dream” when it happened. I believe that the evoked autonomic system from dreaming can create significant physiological trouble to our body.

  3. There are three paragraphs under the subtitle “Why is REM sleep important” and yet the question in that subtitle is not addressed until toward the end of the third paragraph which to paraphrase, says maybe the brain is storing information from the day.

    Per a not-reliable source, my Fitbit watch, I am getting no REM sleep at night. Just in case the watch is approximately correct that I don’t get enough REM sleep, I am looking for what harm may occur or what symptoms to expect. This is the second article so far dedicated to REM sleep that has a lot of talk but doesn’t answer the question presented: Why is REM sleep important.

  4. Glycine, either in the pure form or in collagen helps increase REM sleep. This is sort of anecdotal but i also saw an increase with my sleep tracker.

  5. No, you cannot teach yourself to sleep in REM stages more often. However, you may be able to get more just by going to sleep earlier or doing things such as calm activities an hour before bed and turning off electronics as well (i.e; phone, tv, computer...)

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