WHAT IS R.E.M. SLEEP?

The dream stage of sleep, based on its unique neurochemical composition, provides us with a form of overnight therapy, a soothing balm that removes the sharp edges from the prior day’s emotional experiences.

For people with PTSD, this overnight therapy may not be working effectively, so when a flashback is triggered by, say, a car backfiring, they relive the whole visceral experience once again because the emotion has not been properly stripped away from the memory during sleep.
— Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley and senior author of the study to be published in the journal Current Biology.

The discovery of rapid eye movement (REM), in 1953 led to many studies on brain activity and consciousness.  Using an EEG machine, researchers are able to record the four main brain wave states that occur while awake and asleep.  

Beta - Happens when you are actively awake and aware.

Alpha - There is an awake part and an asleep part to the Alpha brain wave. While awake you experience this brain wave when in deep relaxation, meditation, or daydreaming.  You also experience this brain wave as you fall asleep, and as REM sleep occurs.  

Theta - The next level of sleep, where brain waves are slower in frequency. (non-REM)

Delta - The deepest level of sleep, where brain waves are the slowest in frequency. (non-REM)

At night we cycle through all three brain waves again and again.  Each cycle lasts approximately 90 minutes.  In which we go deeper and deeper into sleep, into the Delta brain wave, and then back up to Alpha where we experience about 20 minutes of REM sleep.  And then the cycle repeats until we wake up.

REM Sleep is notably found to have increased brain activity, breathing becomes rapid, and the eyes move back and forth in all directions.  This is the stage of sleep where dreams seem to occur.  

In studies where people and animals have been purposely deprived of REM sleep (allowed to go into non-REM sleep, but woken up just before the REM sleep stage), it has shown to cause many physical and psychological issues, and if deprived long enough, in animal studies, eventually death.  

REM Sleep is notably found to have increased brain activity, breathing becomes rapid, and the eyes move back and forth in all directions.  This is the stage of sleep where dreams seem to occur.  "UC Berkeley researchers have found that during the dream phase of sleep, also known as REM sleep, our stress chemistry shuts down and the brain processes emotional experiences and takes the edge off difficult memories." - news.berkley.edu

"This study, which shows that rapid-eye movement sleep can decrease emotional intensity in reaction to past events, is the first to systematically test how sleep affects reactivity to previous emotional experiences at both a brain and behavioral level." - dailycal.org

In studies where people and animals have been purposely deprived of REM sleep (allowed to go into non-REM sleep, but woken up just before the REM sleep stage), it has shown to cause many physical and psychological issues, and if deprived long enough, in animal studies, eventually death.  

We believe this unique brain state helps to put these emotional experiences ‘in perspective’ by integrating them with previous memories while ‘stripping away’ the emotional tone associated with them.
— Els van der Helm, UC Berkeley psychology doctoral student

Photo courtesy of NASA,ESA, M. Robberto (Space Telescope Science Institute_ESA) and the Hubble Space Telescope Orion Treasury Project Team2.