NREM is for the Non-Rapid Eye Movement. Technically both light sleep and SWS are a type of NREM.
LNREM is for Light NREM. Most polyphasic sleepers consider light sleep to be a useless and intermediate sleep stage, thus we try to reduce it as much as possible. Also known as Stage 1 and 2 sleep.
A nap is a sleep that usually contains light and REM sleep, only lasting 18-26 minutes.
A core is sleep that contains both SWS, NREM and REM, and can last from 30 minutes to 1.5h, all the way up to 12h.
Sleep pressure is how much a body requires a certain stage of sleep. If REM pressure is highest, the body will try to get REM sleep over stages with lower pressure. If SWS pressure is highest, the body will try to get SWS over stages with lower pressure.
Analogy of sleep and the body
Imagine, if you will, your brain as an automobile. As you use your car each day it gets dirty in the rain and mud (synaptic stress) getting you from A to B (thinking).
Each day the car becomes dirtier until the windscreen gets blocked up and you can no longer drive safely as you have no perception of the road (REM sleep deprivation).
You decide to take your car for a wash through an auto-washer, but there is a big line (light sleep).
You check your oil and it is dirty (Slow Wave Sleep deprivation).
Dirty oil can result in wearing away at your parts, lower efficiency (athletics), more fuel consumption (hormones) and eventually engine failure (blacking out).
You stop the car to change the oil (Slow Wave Sleep) and continue down the line into the car wash.
When you wash your car (brain) you turn things back on and drive through the washer (REM sleep). If you do not get a good amount of time in the washer (15mins) then your car (brain) comes out still dirty (REM deprivation) and you need to wash again.
After the car wash, you look at your fuel gauge and you are empty so decide to fuel up (eat food). You decide you want the higher octane fuel (low-GI nutrient-dense carbs or fats) rather than the lower octane fuel (sugar). Now your car (brain) is ready to drive again at the optimal performance (live life!) and you go on your way.
From this analogy you can see how REM (washing) is most effective when it happens often, and REM deprivation (dirtiness) is quite obvious; SWS is just as important, but you can get away with less of it if you really needed to, and symptoms of SWS deprivation (dirty oil) do not become apparent until things start breaking down. Food is vital to keep your brain running, but there are good and bad choices of food to fuel your brain with.
How Polyphasic Sleep Works!
All schedules go through three adaptations: ultradian rhythm entrainment, and sleep repartitioning and circadian rhythm entrainment. These might be some new words to you, but just relax! If you don’t understand you can learn later.
The ultradian rhythm controls when you wake up, and when you feel sleepy. You will experience this throughout the day as waves of wakefulness and drowsiness. The only way to improve the ultradian rhythm is to try to sleep according to a consistent rhythm and be awake for the same amount of time between periods of sleep.
Sleep repartitioning is when the body diverts from the automatic 1.5h sleep stage consisting of stage 1, stage 2, stage 3 (SWS) then REM. Normally we progress through S1, 2, 3, 4 finally to REM. If an 8h sleeper had a 20-minute nap, it will at first consist of only stage 1 and 2 sleep as per the first 20 minutes of their normal sleep.
With time the body will adapt and change a 20-minute sleep by passing through the other phases very quickly and suspending the brain in the REM stage. The body can also change the first portion of a ‘core sleep’ from mostly stages 1 and 2 to mostly stage 3 (SWS), and many other changes like the first and second examples.
Sleep repartitioning depends also on a circadian rhythm which is the body’s tracker for ‘time of day and lighting conditions’. Lastly, the circadian rhythm will change to accommodate a new time of day. With this change will come digestive timing, a definite placement of the ‘graveyard hours’ and a general stability.
Why be a poly-sleeper?
Have more time in your day:
Ever thought you simply do not have enough time in your day to do all the things you wanted to do? Let me scare you a little bit, an average 9h sleeper is cumulatively only awake 227.5 days a year, out of 365 days! Changing to a single nap schedule you can have an extra 40 days a year to do what you want. That is like getting a free week’s holiday! Alternatively, if you cut down to only 3h sleep a day, you can improve that to an extra 91 days a year (an extra 3 months you never had). In the long run, your life will be effectively longer and you will live more years in a younger body!
‘Although it’s a common belief that 8 hours of sleep is required for optimal health, a six-year study of more than one million adults ages 30 to 102 has shown that people who get only 6 to 7 hours a night have a lower death rate. Individuals who sleep 8 hours or more, or less than 4 hours a night, were shown to have a significantly increased death rate compared to those who averaged 6 to 7 hours. ‘
Many may like to point out ‘or less than 4 hours a night’, but these individuals also were tested to get far less REM and less SWS than the suggested amount. Polyphasic sleep depends on the fact that you are getting the same amount of REM and SWS as you do monophasically. A 4h monophasic sleep will not be the same quality sleep as 4h polyphasically.
Become a better learner:
For humans taking a 90-minute nap “…containing both SWS and REM sleep… performance over 24h showed as much learning as is normally seen after twice that length of time. Thus from the perspective of behavioral improvement, a nap is as good as a night of sleep for learning. Ref: http://www.learningace.com/doc/1120222/1a85d23d9e16600aa31e638585176068/118natneuro_mednick_brief
Elevate your mood:
Sleeping too much has been linked to depression. Many adapted poly-sleepers have anecdotal evidence for feelings of euphoria, elevated mood, better social skills, and increased happiness.
Dream More (Lucidly):
Because you are sleeping more often and getting dream-full REM in your multiple periods of sleep, you will be dreaming more! Many polysleepers are also practiced Lucid Dreamers, as they go hand in hand. Even without Lucid Dreaming techniques, many polysleepers experience frequent lucid dreams.
Risks of poly-sleep:
With reduced light sleep, there is reduced Sleep Spindles and K-complexes. Researchers think that Sleep Spindles are the brain learning about what nerves control what specific muscles when asleep. Sleep spindle activity has furthermore been found to be associated with the integration of new information into existing knowledge as well as directed remembering and forgetting (fast sleep spindles). These are all associated with the young, and it is not know how these processes are important to adults.
The K-complex’s suggested function is aiding the activation homeostasis of synapses and memory consolidation. The activation thresholds of cortical synapses become raised during wakefulness as they process information, and so need to be adjusted back to preserve their signal-to-noise ratio. The down-state provided by K-complexes does this by reducing the strengths of synaptic connections that occur when they are activated while an individual is awake. Further, the recovery from the down-state they induce allows that “cortical firing ‘reboots’ in a systematic order” so that memory engrams encoded during neuronal firing can be “repeatedly practiced and thus consolidated”. This having been said, there are many recorded instances of humans with a genetic mutation causing them to only sleep 2-4 hours a day (and thus having little or no Spindles or Complexes) and still living a perfectly normal healthy life.
There is also evidence that extremely short sleepers may have shorter lifespans if we are anything like Shake Flies.
Age and need for sleep-totals
As a person gets older, their need for sleep becomes less and less over time. That is not to say it is healthy for them to have less sleep, but they can ‘get by feeling fine’ with less. An 18-year-old may be needing a full 3h total sws/rem, whilst a 40-year-old may feel just as energetic and aware on 2.5h total sws/rem. This phenomenon also stretches across to body size, where sometimes a taller larger person can get away with less sleep than a shorter smaller person.
Often it has been discussed that teenagers are in need of more sleep than adults (10h monophasic). This may reflect upon polyphasic sleep, a teenager should be aiming to get more REM than the usual adult, at least 2 hours REM a day. This may mean an extra nap or a longer core. It is not yet suggested children (who need even more sleep) experiment with a reduced sleep polyphasic schedule, though it is still healthy for a child to sleep polyphasically.
Why not to polysleep?
There are several things that will work against you and your adaptation, some of these include:
Poor Health – if you are currently sick, or have a poor immune system the initial sleep deprivation may make things worse. Often people have gotten sick in the first 2 days of adaptation because they are one bad sleep around the corner from a cold or flu. Much like REM suppression, there is an immunity suppression in the beginning stages of sleep deprivation. This is another reason to do an exaptation rather than a traditional adaptation because the faster you go through the suppression stage, the less time you have to get sick and the healthier the adaptation will be.
Poor Diet – it is suggested you fix your diet by cutting out refined foods and sugars so that your insulin sensitivity and blood sugar levels are even, this helps control your weight and your immune system. You will have better sleep quality if you have better food quality.
Caffeine/Alcohol or substance addiction – your addictions will ruin your sleeping habits and prevent you from getting fast, quality sleep. Stimulants and depressants will generally delay REM or reduce total SWS.