What is sleep?

Sleep is a normal active state of all living creatures in which the mind and body are less responsive. It is believed that sleep is a restorative process.

We take sleep for granted, and most of us have probably never asked ourselves – what actually is sleep? Well, the definition of ‘sleep’ is that it’s a naturally recurring state of mind that’s characterized by altered consciousness, the inhibition of almost all voluntary muscles, generally inhibited sensory activity, and a marked reduction in our interactions with our surroundings.

We distinguish sleep from wakefulness by our lack of ability to react to stimuli; however, sleep is more easily reversed than the states of being comatose or being in hibernation.

sleeping person 04 (5)

What is REM?

REM, or Rapid Eye Movement is just one of the five stages of sleep that people experience. REM is characterized by quick and random eye movements, which includes paralysis of the muscles. When we’re asleep, most animals’ systems move to an anabolic state in order to build up the immune, muscular, skeletal and nervous systems.

In non-human animals, sleep is observed in mammals, reptiles, birds, fish, amphibians, and in some form even in insects and nematodes.

Humans have an internal circadian (24-hour) biological clock which naturally promotes sleep at night, even without light fluctuations; whereas sleep is promoted during the day in nocturnal organisms, like rodents. But we do know that sleep patterns vary a lot among individual humans and among animals. Over the past 100 years, artificial light and industrialization have substantially changed human sleep habits, and today the diverse purposes and mechanisms of sleep are still the subject of ongoing research. It appears that sleep assists animals with improvements to both the body and the mind.


One well-known feature of sleep in humans is dreaming, and we’ve all experienced dreams. Whilst oftentimes difficult to describe, dreaming is an experience generally recounted in narrative form and which, while in progress, resembles waking life. However, later, it can usually be distinguished as fantasy.

Sleep Disorders

There are many sleep disorders that humans suffer from; including dyssomnias such as Sleep Apnea, Hypersomnia and Insomnia; Bruxism; parasomnias such as REM Behavior Disorder and Sleepwalking, and Circadian Rhythm sleep disorders. Sleep disorders can lead to chronic sleep deprivation.

This Physiology Hypnogram shows sleep cycles between midnight and 6.30 am – starting with deep sleep. There’s more REM before waking (marked red). Today’s hypnograms are reflective of the quite recent decision to combine NREM stages 3 and 4 into one single stage – Stage 3.

With both birds and mammals, sleep can be divided into two broad types: REM (rapid eye movement) sleep and NREM or non-REM (non-rapid eye movement) sleep. Each type of sleep can be associated with its own distinct set of neurological and physiological features. We know that REM sleep is associated with desynchronized and faster brain waves, dreaming, suspension of homeostasis, and loss of muscle tone. In fact, REM and non-REM sleep are so entirely different that physiologists have classified them as distinct behavioral states. The three major modes of consciousness, physiological regulation and neural activity are represented by REM, non-REM, and waking.

According to the proposed 1975-1977 Hobson and McCarley activation synthesis hypothesis, the alternation between non-REM and REM sleep can be defined by way of influential neurotransmitter systems that cycle reciprocally.

More Sleep Statistics.

Why do we sleep?

Nobody knows why all creatures evolved the need to sleep. What we do know is that all creatures sleep – and that it is a basic biologic need just like breathing and eating. When we deprive ourselves of sleep, we have a rebound period in which we sleep more. This suggests that sleep is necessary for normal life.There are many studies that demonstrate that when subjects are deprived of sleep, that they do not function at their optimum.

How Important Is Sleep?

moon and sleep

Things You Should Know about Sleep

Generally, sleep is the natural state of the body and mind that characterizes an altered consciousness. In the process, there is relative inhibited sensory activity in the mind that allows the muscle to work voluntarily. Once a person is asleep, interaction with his environment is reduced.

Comparatively, when the person is awake, his capacity to react to stimuli is increased as he become more aware of his environment. However, during a state of hibernation, the body is in coma that it can no longer sense the activities in his environment. We sleep in repeated periods at which the body does an alternating different sleeping modes that are popularly known as REM and non-REM. To differentiate, REM is for rapid eye movement however, it is important to take note that it includes several distinct aspects such the virtual paralysis. At this state, the ability of your eye to visualize the events in the surroundings is deactivated. On the other hand, the non-REM is the state wherein our brain utilizes lesser energy while you are asleep. In specific areas of the brain where reduced activity is present, the brain works in restoring the supply of energy in the event. Although it can only be for a short period of time, it allows your body to transport energy all throughout its part.

When we’re asleep, most of our body system goes through the anabolic state wherein some of the system undergoes the process of development such as the immune system. Sleep is not only for humans but also to mammals, amphibians, fish, and to almost all animals. It serves as our way of getting relief from the stressful activities that we did throughout the day. As we sleep, the internal circadian clock stimulates the need of the body to hibernate every single day during rest period through sleep.

It is important to understand that sleep patterns will vary among humans and animals. Basically, humans are diurnal beings that mean we sleep at night whereas; rodents and some animals are nocturnal species that sleep in the day. As much as we need sleep, these living organisms also need to hibernate each day to regain their strength.

Most ongoing researchers today are focused with the different purpose of sleep and its mechanisms. This subject offers substantial result to men as it will broaden our knowledge about it. Previous researches have proven that sleep helps in assisting animals in improving their mind and body. This is because they go through the state of developing of some of their body systems. On humans, the most common encounter when we’re asleep is the dream. This typical experience is a narration of what we encountered while our mind and body are unconscious. Psychology experts would say that dreams are just the realization of all our fantasies in life. Sleep is the time when our mind works in pursuing our aspirations and make them come true by dreaming. The ongoing researches that study about sleep introduced the discovery of other neurological and psychological features.

How to Fall Asleep

The above pieces uses material from the Wikipedia article:
Quotes about sleep:

The woods are lovely, dark and deep. But I have promises to keep, and miles to go before I sleep. -Robert Frost

The nicest thing for me is sleep, then at least I can dream. – Marilyn Monroe

 Now, blessings light on him that first invented sleep! It covers a man all over, thoughts and all, like a cloak; it is meat for the hungry, drink for the thirsty, heat for the cold, and cold for the hot. It is the current coin that purchases all the pleasures of the world cheap, and the balance that sets the king and the shepherd, the fool and the wise man, even.  – Miguel de Cervantes

Think in the morning. Act in the noon. Eat in the evening. Sleep in the night. – William Blake


If you’re going to do something tonight that you’ll be sorry for tomorrow morning, sleep late. – Henry Youngman

Sleep is the best meditation – Dalai Lama
I think the best way to get a good night sleep is to work hard throughout the day. If you work hard and, of course, work out. – William McRaven
Though sleep is called our best friend, it is a friend who often keeps us waiting! – Jules Verne
Sleeping is no mean art: for its sake one must stay awake all day. -Friedrich Nietzsche
Sleep is perverse as human nature,
Sleep is perverse as legislature….
So people who go to bed to sleep
Must count French premiers or sheep,
And people who ought to arise from bed
Yawn and go back to sleep instead. – Ogden Nash
It’s at night, when perhaps we should be dreaming, that the mind is most clear, that we are most able to hold all our life in the palm of our skull. I don’t know if anyone has ever pointed out that great attraction of insomnia before, but it is so; the night seems to release a little more of our vast backward inheritance of instincts and feelings; as with the dawn, a little honey is allowed to ooze between the lips of the sandwich, a little of the stuff of dreams to drip into the waking mind. I wish I believed, as J. B. Priestley did, that consciousness continues after disembodiment or death, not forever, but for a long while. Three score years and ten is such a stingy ration of time, when there is so much time around. Perhaps that’s why some of us are insomniacs; night is so precious that it would be pusillanimous to sleep all through it! A “bad night” is not always a bad thing. -Brian W. Aldiss
People say, ‘I’m going to sleep now,’ as if it were nothing. But it’s really a bizarre activity. ‘For the next several hours, while the sun is gone, I’m going to become unconscious, temporarily losing command over everything I know and understand. When the sun returns, I will resume my life.’

If you didn’t know what sleep was, and you had only seen it in a science fiction movie, you would think it was weird and tell all your friends about the movie you’d seen.

They had these people, you know? And they would walk around all day and be OK? And then, once a day, usually after dark, they would lie down on these special platforms and become unconscious. They would stop functioning almost completely, except deep in their minds they would have adventures and experiences that were completely impossible in real life. As they lay there, completely vulnerable to their enemies, their only movements were to occasionally shift from one position to another; or, if one of the ‘mind adventures’ got too real, they would sit up and scream and be glad they weren’t unconscious anymore. Then they would drink a lot of coffee.’

So, next time you see someone sleeping, make believe you’re in a science fiction movie. And whisper, ‘The creature is regenerating itself. – George Carlin

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