REM sleep is 'magical': experts explain why it's so important

Any sleep monitor shows you that sleep is far from being a passive matter.

And no stage of sleep reflects this better than rapid eye movement, or REM, and also REM, commonly called

.

"It's also called paradoxical sleep and active sleep, because REM sleep is actually

," explains Dr. Rajkumar Dasgupta, a sleep medicine expert and pulmonary specialist at the Keck School of Medicine at the University of Southern California.

Before scientists discovered REM sleep in the 1950s, it wasn't clear that anything happened in the brain at night.

But today researchers understand sleep as a very active process made up of different types of rest, including REM sleep, which in a sense doesn't look like rest at all.

While the body is often "Off" during REM sleep,

.

It is generating intense dreams and equally synthesizing memories and knowledge.

Scientists are still working to unravel how exactly this strange state of consciousness works.

"It's fair to say that a lot remains to be learned about REM sleep," said Dr. Dasgupta.

But as far as researchers do know, REM sleep is critical to our emotional health and brain function, and potentially even our longevity.

What place does REM sleep occupy in the sleep cycle?

Throughout the night, "we drift in and out of the rhythmic, symphonic pattern of the different stages of sleep: non-REM 1, 2, 3 and REM," said Rebecca Robbins, a professor of medicine at Harvard Medical School and a scientific associate in the division of sleep and circadian disorders at Brigham & Women's Hospital.

When a person falls asleep, they enter the first phase of non-REM sleep.

This stage lasts less than 10 minutes and is considered

.

Breathing and heart rate slow and

as you enter the second stage of non-REM sleep, where body temperature drops and brain waves slow.

You then enter the third phase, known as deep sleep, in which the body

, strengthens your immune system, releases hormones, and restores your energy.

After that, REM sleep begins, in which your heart rate, breathing, and brain activity increase.

The brain regions involved in processing emotions and sensory information (from the world of your dreams) are turned on.

Meanwhile, your brain

, preventing you from acting out your dreams, as detailed by Dasgupta.

In theory, you go through the four phases in

, which on a normal night are repeated four to six times.

Finally, after the last REM cycle has passed, the person wakes up rested and alert, according to Dr. Indira Gurubhagavatula, a sleep specialist at Penn Medicine and an associate professor of medicine at the Philadelphia VA Medical Center.

What are the benefits of REM sleep?

If you've ever gone to bed restless about something and woken up with noticeably less worry, it's likely due to the

and memory reconstitution that occurs during REM.

The brain has been shown

, removing the "sharp, painful edges" of life's difficulties, said Matthew Walker, a professor of neuroscience and psychology and founder and director of the Center for the Science of Human Sleep at the University of California at Berkeley.

REM sleep is "like a form of

overnight

The REM stadium also allows us

.

During this phase of sleep, the brain reinforces neural connections formed by the previous day's experiences and integrates them into existing networks, Dr. Robbins added.

Matthew Walker expanded on it: "We took those new bits of information and started to match them against our previous catalog of accumulated information. It's pretty much

."

These new connections also make us

.

"We wake up with a revised mental network of associations" that helps us solve problems.

Researchers in Professor Walker's laboratory carried out a small study in which they woke people in different stages of sleep and asked them to solve anagrams.

They found that people who were awakened from REM sleep solved 32% more anagrams than those who were interrupted from non-REM sleep.

And then, of course, there are dreams: most of the most vivid ones take place during REM sleep.

Some experts suspect that dreams are a mere byproduct of REM sleep, the mental manifestation of neurological work.

But others believe they can help people

, Walker said.

And while most physical processes, such as the repair of bone and muscle tissue, happen during non-REM sleep, some hormonal changes take place while a person is in REM, Walker specified, including the release of

( peaking at the start of the first REM cycle).

Adults should aim to get seven to nine hours of sleep each night.

Photo Shutterstock.

What happens if you don't experience enough REM?

Genetics and other factors can influence how much sleep is needed, but most adults should aim to get

, which includes about two hours of REM sleep, Indira Gurubhagavatula said.

In general you need less sleep as you get older, even slightly less REM sleep.

But large REM sleep deficits, whatever your age, can rob you of its psychological benefits, Rajkumar Dasgupta warned.

You may have greater difficulties learning, processing emotional experiences, or solving problems.

Dysregulated REM sleep is also linked to cognitive and mental health problems, on the order of

, according to Dr. Ana Krieger, medical director of the Center for Sleep Medicine at the prestigious Weill Cornell University.

Too little REM, fragmented REM, and REM sleep behavior disorders—in which muscle paralysis does not occur and people physically enact their dreams, often by kicking or punching—are associated with neurological, from mild forgetfulness to dementia and Parkinson's disease.

A 2020 study of more than 4,000 middle-aged and older adults found that every 5% decrease in REM sleep was associated with a 13% increased risk of dying from any cause in the next two decades.

Lack of sleep is generally associated with death, but research reveals that not getting enough sleep during REM periods "is the single most determining factor of all stages," according to Walker.

Neither he nor other experts are sure how to interpret this relationship between REM sleep and mortality.

"I think we still don't understand REM sleep well enough to say definitively what mechanisms are at play," the professor mused.

Or, as Dr. Gurubhagavatula put it, if the lack of REM sleep is really causing the death.

How do you know if more is needed?

Gurubhagavatula argues that it's hard to distinguish the signs of REM sleep deprivation from sleep deprivation in general.

If someone is sleep deprived, they probably have REM sleep deprivation.

However, certain behaviors can specifically compromise your REM sleep.

"Cutting your sleep short by going to bed late and then using your alarm clock to get up can put you at risk of chronic REM sleep deprivation," she said.

This is because the longest REM periods tend to occur at the end of the night.

Drinking alcoholic beverages before bed also "markedly impairs your REM sleep," Walker said, because the process of metabolizing alcohol produces compounds that affect regulation of the sleep cycle.

What's more, Gurubhagavatula said, moderate to heavy drinkers are at higher risk of

REM sleep

Antidepressants can also reduce REM sleep or trigger behavioral disorders in that phase.

In addition, according to Dr. Dasgupta, certain conditions—such as narcolepsy, obstructive sleep apnea, and depression—can increase the risk of REM sleep abnormalities.

When you suffer from any of these conditions and you perceive a lack of sleep, it is necessary to consult a sleep specialist.

In the case of sleep apnea, for example, "as soon as we start therapy, people often have a spike in REM sleep," Dasgupta said.

Keeping regular times to get up and go to bed is key when it comes to "ordering" sleep.

Photo Shutterstock.

Is it possible to prioritize REM sleep?

Although recent research indicates that people may have slightly more REM sleep in winter, it's a modern myth that you can select a specific stage of sleep to enhance it.

"People want to manipulate sleep and get more out of this particular phase, but

," Dr. Krieger said.

The natural architecture of sleep is not something to be tinkered with, but something to be protected.

"The way to achieve healthy REM sleep is to take care of

and let your brain do the rest," Gurubhagavatula said.

Getting up and going to bed at the same time each day helps the brain and body know when to rest, making sleep more efficient, Rebecca Robbins stressed.

Other behaviors that help regulate the biological clock are having a consistent meal schedule and

, exercising regularly, getting some sun in the morning, and avoiding bluish light in the evening.

Be sure to maintain other good sleep hygiene practices, such as avoiding alcohol and stimulants like caffeine and nicotine (particularly late in the day) and maintaining a dark, quiet, and cool sleep environment, Indira Gurubhagavatula said.

And don't forget the importance of a wind-down routine to help transition you from the action to a night of rest and recovery, including that weirdly busy time your brain spends during REM sleep.

© The New York Times

Translation: Roman Garcia Azcarate

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These notes may interest you:

➪How to control the negative thoughts that assail us at night and do not let us sleep

➪Sleep paralysis, a distressing and frequent episode: what it is and when to consult

➪What is restless leg syndrome and why it can affect your sleep

➪All this happens in your brain while you sleep (and that is why it is so important to rest well)

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