Larry A. Law
Non-Rapid Eye Movement (NREM) sleep consists of slow, repeating waves with occasional bursts of activity called sleep spindles. Sleep spindles shield the brain from external noises. The more sleep spindles you have, the more resilient your sleep will be. People who don't have as many sleep spindles are more easily awakened by noise.
NREM waves are generated in the middle of the frontal lobe and move from the front of the brain to the back. Thousands of brain cells unite and fire at the same time. This is called neural synchrony. Toxins in the brain are flushed out during NREM sleep in a process called neural sanitation. This is accomplished via the glymphatic system which consists of glial cells located next to the neurons. This system drains contaminants from the brain just like the lymphatic system does for our body. It's one reason why our sleep is so important as it's a powerful cleanse getting rid of amyloid plaque like tau, which is a plaque associated with Alzheimer’s disease.
NREM sleep is also responsible for the file transfer process which moves fragile, short-term memory in the hippocampus (where the short-term memory is stored) to more permanent, safer long-term storage in the cortex. This enables the brain to reflect upon outside world experiences gathered during the day and distill the lessons learned from those experiences. In this way, the brain stores and strengthens new facts and skills. The first part of sleep, early in the sleep cycle, is rich in NREM (compared to Rapid Eye Movement (REM) sleep) and it provides the superior memory retention and even the selective forgetting we need. Who knew we needed to forget in the night! But if you think about it, our forgetting helps us to put aside all the trivial things we can get bogged down with. That is also a kind of cleanse.
There is an interesting thing to observe in someone who is drifting off to sleep and entering Stage 1 of NREM sleep. Their eyes will gently begin to roll in their eye sockets in perfect dual harmony. It can be seen through their eyelids, but an observer must be careful not to freak them out by waking them while they are being watched! Another interesting feature of NREM sleep is that a person does not dream during this stage. You have to be in REM sleep to dream.
REM sleep is called paradoxical sleep. The brain appears to wake up but the body is asleep. In fact, the body is completely paralyzed during this cycle. Muscles don’t respond to what you are dreaming so you don’t hurt yourself by acting out your dreams! Your body is completely limp like a rag doll. Involuntary muscles (breathing, heartbeat, etc.) continue to work, but voluntary muscles in your limbs do not respond to what your brain is experiencing.
During REM sleep, signals, emotions, motivations, and memories (past and present) are all played out on the big screen of the brain’s visual, auditory, and kinesthetic sensory cortices. This type of sleep integrates/blends, interconnects, and expands details of memory to make a more accurate model of how the world works. It also allows you to create innovative insights and solve problems. Creativity is a priority of REM sleep. Bizarre algorithms work towards making connections between vast stores of information. They enable us to make non-obvious associations. Insight and inspiration come during this type of sleep. Anyone who has gotten up from a deep, peaceful, restful sleep and has an ahha moment or flash of insight from a waking world problem will recognize how important REM sleep is!
So, how do we ensure we get enough sleep spindles? How do we make sure our NREM and our REM is maximized for our optimal benefit? No one really knows, but my guess is our diet and the nutrition in it play a big part of that! To learn more on how a person can improve their nutrition, see my book. For my wife, Angie, it took her two years of consistent, good nutrition before she began sleeping through the night without waking up or knowing she was trying to sleep! This was a huge benefit for her health and a welcome gift to finally be sleeping well each night.