Any sleep monitor will show you that light sleep is far from a passive process, and no stage of sleep demonstrates this better than rapid eye movement, or REM, often referred to as the dream stage
.
"It's also called paradoxical sleep or active sleep, because REM sleep is so much like being awake," said Rajkumar Dasgupta, a sleep medicine and pulmonology specialist at the University of Southern California Keck School of Medicine.
"Sleeping Girl" by Roy Lichtenstein, an iconic work of Pop Art from 1964 EFE/Sotheby's
Before the 1950s, when scientists discovered REM sleep, it wasn't clear that much happened in the brain at night;
however, current researchers understand sleep as a very active process made up of different types of rest, including REM sleep, which in a way does not look like rest at all.
While the body is often “off” during REM sleep, the brain is quite “on” as it is generating vivid dreams and synthesizing memories and knowledge.
Scientists are still working to unravel how exactly this
strange state of consciousness works.
"It's fair to say that there's still a lot to learn about REM sleep," Dasgupta said, but as far as researchers know, REM sleep is critical to our emotional health and brain function, and perhaps even to our longevity.
What place does REM sleep occupy in the sleep cycle?
Throughout the night, "we drift in and out of this symphonic, rhythmic pattern of different stages of sleep: non-REM 1, 2, 3, and REM," said Rebecca Robbins, a professor of medicine at Harvard Medical School. and Associate Scientist in the Department of Circadian and Sleep Disorders at Brigham and Women's Hospital.
When you doze off, you enter the first phase of non-REM sleep.
It lasts less than 10 minutes and is considered light sleep.
Breathing and heart rate slow and muscles relax as you enter the second phase of non-REM sleep, in which body temperature drops and brain waves slow.
You then enter the third phase, known as deep sleep, in which the body repairs bones and muscles, strengthens the immune system, releases hormones, and regains your energy.
Then the REM phase begins, in which the heart rate, breathing and brain activity increase.
The brain regions that process emotions and sensory information (from the dream world) turn on.
Meanwhile, the brain paralyzes the muscles in the arms and legs, preventing the patient from acting out their dreams, Dasgupta explained.
Ideally, go through the
four phases in cycles of 90 to 110 minutes
that are repeated four to six times on a typical night.
After the last REM cycle, you wake up rested and alert, said Indira Gurubhagavatula, a Penn Medicine sleep specialist and associate professor of medicine at the Philadelphia VA Medical Center.
What are the benefits of the REM phase?
If you've ever gone to sleep angry about something and woken up much less upset, it's likely due to the emotional processing and memory reconsolidation that occurs during REM sleep.
The brain has been shown to separate memories from their emotional baggage and remove the "sharp, painful edges" of life's difficulties, said Matthew Walker, professor of neuroscience and psychology and founder and director of the Center for the Science of Human Sleep. from the University of California at Berkeley.
REM sleep is "a kind of
night therapy
," Walker said.
The REM phase also makes us better at learning.
During this phase of sleep, the brain reinforces the neural connections formed by the previous day's experiences and integrates them into existing networks, Robbins explained.
Walker added:
“We take these new bits of information and start matching them against our catalog of stored information.
It is almost a kind of
informational alchemy
”.
Of course, then there is the dream phase: most of our vivid dreams take place during the REM phase.
Some experts suspect that dreams are merely a byproduct of REM sleep, the mental manifestation of neurological work, but others believe they can help people process painful experiences, Walker said.
And while most physical processes, such as the repair of bone and muscle tissue, occur during non-REM sleep, some hormonal changes occur while a person is in the REM phase, Walker explained, such as the release of testosterone (peaking at the start of the first REM cycle).
What happens if you don't get enough REM sleep?
Genetics and other factors can influence how much sleep is needed, but most adults should aim for seven to nine hours of sleep each
night
, including about two hours of REM sleep, Gurubhagavatula said.
In general, you need less sleep as you get older, including slightly less REM sleep;
however, a significant REM sleep deficit, regardless of age, can deprive you of its psychological benefits, Dasgupta said.
You may have
a harder time
learning, processing emotional experiences, or solving problems.
Dysregulated REM sleep is also linked to cognitive and mental health problems, such as slow thinking and depression, according to Ana Krieger, medical director of the Weill Cornell Medicine Center for Sleep Medicine.
Lack of REM phase, REM fragmentation, and REM sleep behavior disorder (in which muscle paralysis does not occur and people act out their dreams, often by kicking or punching) are associated with neurological problems,
ranging
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 percent less REM sleep was associated with a 13 percent increased risk of dying from any cause in the next two decades.
Lack of sleep is generally associated with death, but research suggests that not entering REM long enough "is the most important factor of all the stages," Walker said.
Walker and other experts aren't sure what to make of this relationship between REM sleep and mortality.
“I don't think we understand REM sleep well enough to definitively say what mechanisms are at play,” he said.
Or, as Gurubhagavatula said, if lack of REM sleep is the actual cause of death.
How do you know if you have this deficiency?
According to Gurubhagavatula, it is difficult to distinguish between the symptoms of lack of REM sleep and those of general sleep deprivation.
If you haven't slept, you may need REM sleep.
However, certain behaviors can specifically compromise REM sleep.
"Going to bed late and using an alarm clock to get up can put you at risk of chronic REM sleep deprivation," Gurubhagavatula said.
This is because the longest REM periods usually occur
at the end
of the night.
Antidepressants can also reduce REM sleep or
trigger
REM sleep behavior disorder.
In addition, according to Dasgupta, certain conditions, such as narcolepsy, obstructive sleep apnea, and depression, can increase the risk of REM abnormalities.
If you have any of these conditions and feel sleep-deprived, see a sleep specialist.
For example, in the case of sleep apnea, "as soon as we start therapy, people usually go back to REM sleep," Dasgupta explained.
Is it possible to prioritize the REM phase?
Although recent research suggests that people can get a little more REM sleep in the winter, that you can choose a specific stage of sleep and improve it is a modern myth.
"People want to manipulate sleep and spend more time in this particular stage, but the body doesn't work like that," Krieger said.
The natural architecture of sleep is not something that can be manipulated, but it can be protected.
"The way to get healthy REM sleep is to focus on getting a
good night's sleep in general
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, which makes sleep more efficient, Robbins explained.
Other behaviors that help regulate your body clock include having a consistent meal schedule and not eating too late, exercising regularly, getting some sunlight in the morning, and avoiding blue light at night.
Be sure to follow 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, Gurubhagavatula said.
And don't overlook the importance of a wind-down routine to help transition you from action to a night of rest and recovery, including that weirdly hectic time your brain spends in REM phase.
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