Sleep is a vital, complex part of human existence. You instantly know when you’ve had too little or too much and the benefits when you’re well rested.  Many people think sleep is merely a “down time” when the brain shuts off and the body rests, and restless nights can be remedied by caffeine; but how much do we know about sleep?

Sleep, by definition, is a naturally recurring state of relatively suspended sensory and motor activity, characterized by total or partial unconsciousness and the inactivity of nearly all voluntary muscles.  It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and it is easily reversible than hibernation or coma.  With sleep studies done in the past several decades show us that sleep has distinctive stages that cycle throughout the night.  Your brain stays active throughout your entire sleep, but different events happen during each individual stage.

There are several stages in a normal sleep cycle that can be cut into two broad categories: NREM (Non-Rapid Eye Movement) sleep and REM (Rapid Eye Movement) sleep.  Each type has a distinct set of associated physiological, neurological, and psychological features – For instance, certain stages of sleep are indeed for us to feel well rested and energetic the next day, and other stages help us learn or make memories – defragging your brain.

NREM Sleep:

NREM sleep is divided into sections 1 through 3

* Stage 1 – occurs in the beginning of sleep, with slow eye movement. People aroused from this stage often believe that they have been fully awake. During the transition into Stage 1 sleep, it is common to experience random jerking.
* Stage 2 – no eye movement occurs, and dreaming is very rare. The sleeper is quite easily awakened.
* Stage 3, previously divided into stages 3 and 4, is deep sleep, slow-wave sleep (SWS). Dreaming is more common in this stage than in other stages of NREM sleep though not as common as in REM sleep. The content of SWS dreams tends to be disconnected, less vivid, and less memorable than those that occur during REM sleep.

REM Sleep:

Rapid eye movement sleep, or REM sleep, accounts for 20%–25% of total sleep time in most human adults.  Most memorable dreaming occurs in this stage.  At least in mammals, a descending muscular atonia – muscle paralysis – is seen.  Such paralysis may be necessary to protect organisms from self-damage through physically acting out scenes from the often-vivid dreams that occur during this stage.

REM sleep appears to be important for development of the brain.  REM sleep occupies the majority of time of sleep for infants who spend most of their time sleeping.  Among different species, the more premature the baby is born the more time it spends in REM sleep.  There are dangers when you interfere with your REM sleep at an early age.  Babies who experience REM deprivation might result with developmeantal abnormalities later on in life.

Effects Of REM or Sleep Deprivation:

-  Sore muscles and headaches
-  Increase in weight
-  Shaking
-  Hallucinations
-  Loss of memory
-  Bad moods along with Anxiety
-  Very high blood pressure
-  Risk of diabetes
-  Mild psychosis
-   Always tired

Who Sleeps?

Nearly universal, sleep is observed in all mammals, all birds, and many reptiles, amphibians, and fish, though the variation in amount of sleep is staggering.

Bats……………………20 hours
Lions………………….13.5 hours
Laboratory rats……13 hours
Domestics cats…….12.5 hours
Baboons……………..9.5 hours
Humans………………8 hours
Pilot whales…………5.5 hours
Asian elephants……3 hours
Roe deer……………..3 hours
Giraffes……………….2 hours

Infants need nearly as much as 19 hours of sleep daily, but adults on the other hand need a recommended dose of 7-8 hours nightly.  Less than that can cause irritability, loss of coordination, drowsiness, mental, emotional, and physical fatigue.  If you sleep in too much or sleep too little you might be suffering from depression.  If that is the case you may what to contact your doctor.  Studies have showed us that if you don’t get enough sleep as a young kid its possible that it stunts your growth and increases the risk of developing Type 2 Diabetes. Too much sleep, on the other hand, has been shown to considerably shorten your lifespan.  If you need to find a good balance between 7 to 9 hours.

Why Do We Need To Sleep?

This variety in sleep patterns has inspired some evolutionary theories of sleep. One theory is the animals that are at the bottom of the food chain lower sleep less.  This is due to the fear of being attacked.  The weaker the target the faster the sleep.  However, a conflicting theory suggests that sleep protects us from predators, since we are curled up in a quiet place out of harm’s way.

There are four central theories regarding why we sleep – to heal, to rest, to learn and to dream.

Heal - Wound healing has been shown to be affected by sleep, and sleep deprivation can affect the immune system. Sleep quickens cell regeneration and accentuates the growth and rejuvenation of the immune, nervous, skeletal and muscular systems.

Rest - Because being in a hyperactive anabolic state requires so much energy, being awake may only be a temporary state. We use this time to feed and reproduce. That’s all. So why do we sleep? Simply: to gain relief from this hyperactive state.

Learn - In a study by Turner et al, 40 people were allowed only 26 minutes sleep per night. They were given cognitive tests which showed their working memory deteriorated by 38% over four days. Without REM sleep, they found it much harder to complete memory tasks and solve problems.

Dream – No one is quite sure what purpose dreaming serves, but it clearly serves a purpose. Freud’s work concerns the psychological role of dreams, which clearly does not exclude any physiological role they may have. Dreaming appears to be a by-product of REM sleep. So is it possible that the main reason why we sleep is to dream?

Other sleep experiments have shown that “procedural memory” (your ability to perform certain skills) is dependent on REM sleep. Similarly, “declarative memory” (your knowledge of facts) relies on Slow Wave Sleep (NREM).

Benefits of Sleep:

Keeps your heart rate calm and keep colestrial levels low
Best way to reduce stress is having a healthy sleep.  Sleeping will calm your nerves and have a clear mind when you wake up in the morning.
Sleeping improves your memory
Helps weight loss.  You burn the most calories when you sleep and reduces your chance of diabities
Restores your bodies enegry levels

Sleep Quotes:

“Sleep that knits up the ravelled sleave of care
The death of each day’s life, sore labour’s bath
Balm of hurt minds, great nature’s second course,
Chief nourisher in life’s feast”. –William Shakespeare, Macbeth

“There is more refreshment and stimulation in a nap,
even of the briefest, than in all the alcohol ever distilled”. – Edward Lucas

“Life is something that happens when you can’t get to sleep”.  --Fran Lebowitz