Are you experiencing enough REM sleep?
Making memories, dreaming happens in sleep’s busiest phase
Any sleep tracker will show you that slumber is far from a passive affair. And no stage of sleep demonstrates that better than rapid eye movement, or REM, commonly called dream sleep.
“It’s also called paradoxical sleep or active sleep, because REM sleep is actually very close to being awake,” said Dr. Rajkumar Dasgupta, a sleep medicine and pulmonary specialist at the Keck School of Medicine of the University of Southern California.
Before scientists discovered REM sleep in the 1950s, it wasn’t clear that much of anything was happening in the brain at night. Researchers today, however, understand sleep as a highly active process composed of very different types of rest — including REM, which in some ways doesn’t seem like rest at all.
While the body typically remains “off ” during REM sleep, the brain is very much “on.” It’s generating vivid dreams, as well as synthesizing memories and knowledge. Scientists are still working to unravel how this strange state of consciousness works. But from what they do understand, REM is critical to our emotional health and brain function — and potentially even our longevity.
REM sleep and sleep cycles
Throughout the night, “we’re going in and out of this rhythmic, symphonic pattern of the various stages of sleep: non-REM 1, 2, 3 and REM,” said Rebecca Robbins, an associate scientist in the division of sleep and circadian disorders at Brigham and
Women’s Hospital.
As you doze off, you enter the first stage of non-REM. This lasts less than 10 minutes and is considered a light sleep. Your breathing and heart rate decelerate and your muscles relax as you slip into the second stage of non-REM sleep, where your body temperature drops and your brain waves get slower. Then you enter the third stage, known as deep sleep, when your body repairs your bones and muscles, strengthens your immune system, releases hormones and restores your energy.
After that, REM sleep begins, and your heart rate, breathing and brain activity increase. Brain regions involved in processing emotions and sensory input (from your dream world) light up. Meanwhile, your brain paralyzes the muscles in your arms and legs, preventing you from acting out your dreams, Dasgupta explained.
Ideally, you move through the four stages in 90- to 110-minute cycles that repeat four to six times a night. After your last REM cycle, you wake up rested and alert, said Dr. Indira Gurubhagavatula, a sleep specialist at Penn Medicine.
Benefits of REM sleep
If you’ve ever gone to bed upset about something and woken up noticeably less bothered, it’s likely a result of the emotional processing and memory reconsolidation that happen during REM. There’s evidence that your brain divorces memories from their emotional charge — removing the “sharp, painful edges” from life’s difficulties, said Matthew Walker, a professor of neuroscience and psychology and the founder and director of the Center for Human Sleep Science at the University of California, Berkeley. REM is “like a form of overnight therapy,” he said.
REM also makes us better learners. During this sleep stage, your brain strengthens neural connections formed by the previous day’s experiences and integrates them into existing networks, Robbins said.
Walker added: “We take those new pieces of information and start colliding them with our back catalog of stored information. It’s almost a form of informational alchemy.”
Then there’s dreaming: The majority of our vivid dreams take place during REM. Some experts suspect that dreams are a mere byproduct of REM sleep — the mental manifestation of neurological work. Others think dreaming can help with processing painful experiences, Walker said.
Effects of poor REM sleep
Genetics and other factors can influence the amount of sleep you need, but most adults should aim for seven to nine hours each night, which includes about two hours of REM sleep, Gurubhagavatula said.
In general, you need less sleep as you age, including slightly less REM. But large deficits of REM sleep, no matter your age, can deprive you of its psychological benefits, Dasgupta said. You may have more trouble learning, processing emotional experiences or solving problems.
Dysregulated REM sleep is also linked with cognitive and mental health issues, like slower thinking and depression, said Dr. Ana Krieger, medical director of the Center for Sleep Medicine at Weill Cornell Medicine. Too little REM, fragmented REM and REM sleep behavior disorder — where muscle paralysis fails to happen and people physically act out their dreams, often by kicking or punching — are associated with neurological issues, from mild forgetfulness to Parkinson’s disease.
A 2020 study of more than 4,000 middle-aged and older adults found that each 5% decrease in REM sleep was linked with a 13% greater risk of dying from any cause over the next two decades. Lack of sleep in general is associated with death, but the research suggests that not getting enough REM sleep “is the single strongest factor of all stages,” Walker said.
Get better REM sleep
Although recent research suggests people may get slightly more REM sleep in the winter, it’s a modern myth that you can target one specific stage of sleep for improvement. “People want to manipulate sleep and have more of this particular stage, but the body doesn’t function like that,” Krieger said. The natural architecture of sleep is not something to tinker with, but to protect.
“The way to get healthy REM sleep is to focus on getting healthy sleep overall, and let your brain do the rest,” Gurubhagavatula said.
Waking up and going to bed at the same time every day helps your brain and body know when they should be resting, making sleep more efficient, Robbins said. Other behaviors that help regulate your biological clock include having a consistent eating schedule and not eating too late, exercising regularly and getting some morning sunlight.
Make sure to follow other sleep hygiene best practices, such as avoiding alcohol and stimulants like caffeine and nicotine (particularly later in the day) and maintaining a sleep environment that is dark, quiet and cool, Gurubhagavatula said.
And don’t overlook the importance of a winddown routine to help you shift from action to a night of rest and recovery — including that bizarrely busy time your brain spends in REM.