Paradoxical sleep: what is its role?

Paradoxical sleep: what is its role?

Conducive to dreams, paradoxical sleep is one of the stages of sleep. What is its role, what is its duration, what are its benefits on the body and how to preserve it? All the answers from Doctor Nicolas Juenet, psychiatrist and sleep specialist at the Clinique Lyon Lumière.

What is REM sleep?

Sleep comes in several stages throughout the night. REM sleep is one of these stages. There are 4 stages:

  • Light slow-wave sleep 1;
  • Light slow-wave sleep 2;
  • Deep slow-wave sleep;
  • Paradoxical sleep.

These four stages form a cycle. Throughout the night, during our sleep, if there is no interruption, we go through several cycles. “Normally with sufficient sleep time, we perform between 4 and 6 cycles per night, explains Doctor Nicolas Juenet, psychiatrist and sleep specialist at the Clinique Lyon Lumière. “A cycle lasts 90 minutes which corresponds to 6.5 to 8 hours of sleep on average“.

How long does REM sleep last?

In total in a night, paradoxical sleep represents 18 to 20% of the night in a young and healthy subject. REM sleep is produced in very small quantities at the start of the night during the first cycles, then as the night progresses, the proportion of REM sleep in the cycles increases. It usually takes at least 50 minutes of sleep before entering REM sleep.

Sleep is observed using a sleep recording, called polysomnographie. The examination is carried out over one to two nights in a hospital environment. Eight electrodes distributed across the skull record brain activity (basic encephalogram).

What happens during REM sleep?

During the paradoxical sleep stage the brain is particularly active. “We find brain activity almost similar to that of wakefulnessexplains the psychiatrist. Hence its name since there is a paradox between brain activity and the fact that we sleep.. The term “paradoxical sleep” is specific to Europe. In the rest of the world, we rather speak of REM Sleep (Rapid Eyes Movement), an expression linked to the fact that in addition to significant brain activity we have erratic eye movements during our sleep.

What is the role of paradoxical sleep?

Like all stages of sleep, paradoxical sleep has an essential role for physical, but especially mental, well-being. “In neuroscience, we realized that there was a link between paradoxical sleep and memory, the specialist was able to observe. The most plausible explanation is to say that it is during paradoxical sleep that a reprocessing of all the information from the day takes place. Namely the new information that we acquire but also the information that we have in mind (worries, ruminations for example). REM sleep also participates in the regulation of emotions and mood. It helps our brain sort through our emotions. The brain, forced to manage all this confusing information, then develops scenarios which lead to the construction of dreams. We can also emphasize that paradoxical sleep has a major role in infants in the sense that it participates in the maturation of the nervous system. Moreover, at this age, sleep time and its proportion of paradoxical sleep are much greater than in adults.

What are the problems associated with REM sleep?

Lack of paradoxical sleep

This deficiency may come frominsomnia. “Paradoxical sleep is one of the stages strongly affected since it is a stage that we experience in greater quantities, especially at the end of the night, recalls Doctor Nicolas Juenet. If the nights are too short, you automatically don’t meet your needs.” REM sleep deficiency can also be due to abnormality in the sleep processparticularly when taking certain substances including alcohol.

Too much paradoxical sleep

Particularly in the event of depression. “There is a modification in the balance of brain molecules which will promote paradoxical sleep at the expense of other stages, specifies the psychiatrist. On goes to 20-30% paradoxical sleep instead of 18-20%”. The narcolepsy also leads to too much paradoxical sleep.

Alteration of paradoxical sleep quality

The alcohol consumption disrupts the chemical balance of the brain and alters sleep composition, generating more restless and unrestorative nights.

THE antidepressants also reduce the quality of paradoxical sleep. “By reversing the neurobiological imbalances of the brain linked to depression (decrease in dopamine, and especially increase in serotonin and norepinephrine), they will promote a reduction in the proportion of this stage (and therefore a return to normal in cases initial depression)“, explains the expert.

Muscle paralysis

During paradoxical sleep we observe a quasi-paralysis of the voluntary muscles, called “muscular atonia”. “This process, characteristic of paradoxical sleep, is linked to the activation of a structure located in the brain stem and helps prevent us from putting our dreams into practice”describes the psychiatrist.

Sometimes in some people this function blocks. “In certain neurodegenerative diseases, such as Parkinson disease, this structure is destroyed”, indicates the specialist. “The people then live their dream while remaining in their bed and still asleep. We can see them moving with great movements“.

“It’s not about sleepwalking or nightmares, would like to clarify Doctor Nicolas Juenet. Nightmares are dreams, but with negative emotions there is no agitation during sleep. Sleepwalking is an automatic behavior of a brain that has only partially emerged from deep slow-wave sleep and therefore does unsophisticated and automatic things. Unlike REM sleep behavior disorder where actions are developed and in reaction to the subject’s dream.

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How to treat paradoxical sleep disorders?

The mechanics of sleep and in particular paradoxical sleep are complex. Currently, there is no molecule that can restore natural sleep.

The best treatments to restore balanced sleep are behavioral therapies rather than chemical solutions. “This involves paying attention to all the natural regulators of sleep, raises the specialist. Namely: maintain good physical activity during the day, expose yourself to natural light, do not consume stimulants, do not go to bed too late, sleep in silence, in a room at the right temperature, in total darkness without using a screen. The regularity of going to bed and getting up is also very important. Our biological clock is influenced by the day-night alternation. The brain does not know the concept of the weekend. Which means going to bed and getting up at the same time. We remain flexible by shifting the waking time on weekends from 30 minutes to an hour.”.

We remain attentive to the signals sent by our body. Yawning, red eyes indicate that it is time to go to bed. “The good sleep rhythm is the one that comes spontaneously when we remove all constraints”recalls Doctor Nicolas Juenet.

Sleep is one of the pillars of our health. In the event of sleep disorders, it is advisable to make an appointment with your doctor for a clinical examination first and the doctor deems it necessary to carry out a complete assessment.