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Why Dreaming May Be Important for Your Health

Why Dreaming May Be Important for Your Health
From TIME - October 27, 2017

Doctors have warned for years that Americans are not getting enough sleep, with health consequences ranging from drowsy driving and irritability to an increased risk of dementia, heart disease and early death. Now, a recent study suggests that one particular type of sleep may be especially important when it comes to how the brain responds to stressful situations.

The research, published in the Journal of Neuroscience, found that people who spent more time in rapid-eye-movement (REM) sleepthe phase when dreaming occurs had lower fear-related brain activity when they were given mild electric shocks the next day. The findings suggest that getting sufficient REM sleep prior to fearful experiences may make a person less prone to developing post-traumatic stress disorder (PTSD), the authors hypothesize.

The study is not the first to suggest that REM sleep delivers unique benefits. Some experts even believe that it's actually a lack of REM sleep and a lack of dreamingrather than just poor sleep in generalthat's responsible for many of the health problems Americans suffer from today. Here's what scientists know so farand what they suspectabout REM sleep, dreams and what happens when people are deprived of both.

What happens during REM sleep?

Sleep involves five distinct phases, which the brain and body cycle through several times during the night. The first four phases involve a transition from shallow to deep sleep, while the fifth phase, REM sleep, involves heightened brain activity and vivid dreams.

REM sleep stages tend to be relatively short during the first two-thirds of the night as the body prioritizes deeper, slow-wave sleep. And because longer periods of REM sleep only happen during the final hours of sleep (in the early morning, for most people), it can get cut off when you dont spend a full seven or eight hours in bed, says psychologist Rubin Naiman, a sleep and dream specialist at the University of Arizona Center for Integrative Medicine and the author of a recent review about dreaming published in the Annals of the New York Academy of Sciences.

During REM sleep, there is more activity in the visual, motor, emotional and autobiographical memory regions of the brain, says Matthew Walker, professor of psychology at the University of California, Berkeley and author of the new book Why We Sleep. But there is also decreased activity in other regions, like the one involved in rational thoughthence the reason for extremely lucid, but often nonsensical, dreams. (The dreams you remember when you wake up are only part of REM sleep, says Walker; in reality, the brain is highly active throughout the entire phase.)

What happens when you dream?

Scientists are divided as to whether dreams are simply a product of random neurons firing during sleep, or if they are something morelike a data dump that helps the brain separate important memories from non-important ones, or a way for people to prepare for challenges and play through different scenarios in their heads.

Naiman describes the brain during REM sleep as a sort of second gut that digests all of the information gathered that day. Everything we see, every conversation we have, is chewed on and swallowed and filtered through while we dream, and either excreted or assimilated, he says.

What are the health benefits of REM sleep?

Several studies in recent years have suggested that REM sleep can affect how accurately people can read emotions and process external stimuli. Walker's research, for example, has demonstrated that people who achieved REM sleep during a nap were better able to judge facial expressions afterward than those who'd napped without reaching REM.

Walker and his colleagues have also found that people who view emotional images before getting a good night's sleep are less likely to have strong reactions to the same images the next day, compared to those who did not sleep well. I think of dreaming as overnight therapy, Walker says. It provides a nocturnal soothing balm that takes the short edges off of our emotional experiences so we feel better the next day."

Adding to that research, the most recent studyfrom researchers at Rutgers Universitysuggests that the quality of a person's sleep before a traumatic event can play a role in how the brain reacts to a scary situation. "The more REM, the weaker the fear-related effect," the authors write in their paper.

How to get more REM sleep

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