Sleep 101: Why do we sleep? The Basics of Sleep

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Sleep 101: Why do we sleep? The Basics of Sleep

Have you ever given a thought to sleep ...


Have you ever given a thought to sleep, one of our most basic needs? The world of science continues to do research on "sleep", yet there remain still so many unknowns to it, waiting to be discovered! In this article, you will find many interesting facts about sleep, from the definition of sleep to its stages, from why we should sleep, to advice for a good sleep! If you are ready for a little yawn, let’s get started then...

It goes without doubt that sleep is one of the most basic needs of humans. But have you ever wondered why we actually need sleep? I guess the answer is yes like for most people, and what you will find when you do some research is that we need sleep because our brain needs to rest and detox.

But did you also know that sleep can facilitate learning and etch learnings into more permanent storage in our brains? There are chances that you have not heard of this before, because scientific research on "sleep" is still ongoing, and there are still so many unknown aspects to it, waiting to be discovered!

Definition of Sleep

There are many different definitions of sleep, but a simple and comprehensive way to define sleep could probably be this: “A naturally recurring state of resting, characterized by altered consciousness and relatively inhibited sensory activity.” What I want to point out here is that while this definition refers to a relative inhibition of sensory activity (i.e., our 5 senses that we all know so well), it does not mention any inhibition of cognitive activity. This is because our brain is very active and functional while sleeping, which is in fact the most fundamental aspect of sleep that differentiates it from coma, or as it’s popularly known, vegetative state.

To put it in more detail, our level of consciousness is not always the same while asleep. Sleep consists of different stages where our deep and surface layers of consciousness are at different states. These stages follow each other in a cyclic fashion to make up the sleep cycle. On average, a sleep cycle of adults lasts for 90 minutes, which means they go through 4–5 sleep cycles during a 6-hours’ sleep all including two major stages of sleep, namely REM (rapid eye movement) and NREM (non-rapid eye movement).

Sleep Stages


The first stage you change over from wakefulness to sleep is called NREM. Each sleep cycle is calculated to take 90 minutes on average, while NREM accounts for about 60 minutes of it (i.e., NREM makes up about 2/3 of sleep). This stage is where your muscles relax, your heartbeat slows and you fall asleep. It’s very important for your brain to go into deep sleep because this is the stage where cell regeneration takes place, growth hormone is secreted and production of stress hormones is stopped.

Deep sleep comes with several benefits for the whole body, from skin health to the immune system. It promotes healthy growth in children and helps adults get rid of everyday stress, recover and repair themselves both mentally and physically, and secrete hormones of happiness. Especially sleep cycles spent at night between 10.00 p.m. and 03.00 a.m. help you wake up feeling refreshed and happy the next morning, without any dark circles under your eyes!

But why is it so important to sleep especially during these hours of the day? The answer is because our brain goes into deep sleep more easily when it’s dark and secretion of hormones is at a higher rate from 10.00 p.m. to 03.00 a.m. The brain enters a state of deep silence during deep sleep (low frequency EEG activity). You will feel groggy if you wake up, or are woken up, during this stage of sleep as it’s known that sudden changeover from sleep to wakefulness when the brain has not yet completed its sleep cycle may lead to certain problems. Therefore, it’s highly important for your sleep health to arrange your total sleep time in a manner that you will wake up by the end of a full 90-minute sleep cycle. 

Sleeping for minimum one and a half hours will make sure you cycle through the deep and light stages of sleep soundly. Many authorities recommend that you arrange your nighttime sleep in a manner that it will comprise the multiples of a full 90-minute cycle (1.5 hours, 3 hours, 6 hours, 9 hours). You also dream during this stage of sleep, yet these dreams are remembered less often because the brain is not active enough during NREM.


REM sleep is the last stage of the sleep cycle, characterized by rapid eye movement that sets on 60 to 90 minutes after you fall asleep. This is the stage where dreaming occurs. And rapid eye movement is the result of dreaming. This stage where the brain is as active as in full wakefulness is where our dreams occur that we remember as soon as we wake up and are so eager to tell others. The brain can remember those moments as vividly as if they had really happened. The dreams that people think they had all night long actually account for only about 20 seconds of a sleep cycle.

This stage of high brain activity is very important for learning and permanent memory. Everything we learn during the day is taken from short term memory and etched into permanent memory while we sleep. For instance, several studies have proven that students who slept at intervals and got REM sleep during busy studying periods gained better knowledge than those who worked nonstop without taking a sleep break. This is because knowledge in short term memory is doomed to vanish unless processed during REM sleep. Hence, since knowledge is processed and put into permanent storage during sleep, students who get enough sleep wake up with better knowledge of the subjects they studied before sleep. But if you are trying not to learn but just pass the course, staying up all night before taking an exam is a knack peculiar to last exam benders.

Why do we sleep?

Sleep gives the human body the chance to renew its cells, while the brain can delete any redundant information and etch the important ones into permanent storage. Considering the body’s daily activities, getting good and enough sleep is a prerequisite if we are ever to keep up with the pace of life. But why is all this done while asleep and not otherwise? Well, the answer to this remains unknown. Even so, as recommended by doctors, it’s a key factor to sleep minimum 6-8 hours a day depending on the body’s need for sleep, stop food intake 2 hours before sleep, and empty your mind before bedtime. Sleep deprivation can have a pretty bad impact on cognitive and physical activity. Not only sleep deprivation, but poor sleep quality can also have an adverse aftermath. The immune system and several other systems will fail to renew themselves, thus increasing the risk to develop infections and many other diseases (obesity, heart attack, diabetes, hypertension, skin disorders). Memory problems, concentration disorders, and impairments in planning and decision-making mechanisms may occur. The duration of sleep deprivation determines the severity of these symptoms. The more frequent and the longer a person is deprived of sleep, the more chronic become the effects. 72 hours with zero sleep will result in hallucinations and can even have fatal consequences due to severe cell damage. That's why 72 hours is considered the dangerous limit for sleep deprivation. It’s strongly discouraged because its consequences can be devastating.

Tips to improve your sleep

  • First of all, try and figure out a sleep routine that works best for you. As I mentioned before, night sleep is of key importance. Especially sleep between 10.00 p.m. and 03.00 a.m. comes with so many benefits. Yet, it’s still up to you to decide your sleep routine because what really matters is that you set a sleep and wake-up routine that can stick to, day in and day out. Influenced by Cinderella, I prefer to sleep at midnight and wake up at 7.30 in the morning. An important detail when deciding on these hours is to ensure that the hours of sleep you will get is the multiples of a full sleep cycle(3 hours, 4.5 hours, 6 hours or 7.5 hours like me). After a while, this will become an automatic routine thanks to the body’s biological clock.
  • If you cannot fall asleep in about the first 20 minutes in bed, get up immediately or sit up because lying in bed wide awake for a long time will cause you increasing discomfort which will keep you up even longer.
  • Sleeping in dark promotes secretion of several hormones in the brain. Therefore, you should sleep in a quiet, not too hot and preferably dark room for a good sleep. It’s also important to let some fresh air into your bedroom during the day.
  • Another important detail is bed hygiene. Some scientists advise not to make your bed as soon as you get up because otherwise you will cause nothing but trap in your bed the microorganisms that collect in and on it during the night. And there are others who advise to cover your bed with a spread the first thing in the morning to protect it against the dust on the floor. Seems like there is truth to both. To please both stances, my tip would be this: leave your bed unmade in the morning while you keep your windows open to let some fresh air in and then make your bed before you leave the house. How frequently you will change your sheets and pillowcases is entirely up to you.

Tips for people who have trouble sleeping

The first thing you should do is to try and figure out whether your problem is of medical origin. To that end, you can make an appointment with our neurologist and get a sleep test. Our doctor will provide you with all the details you need.

Good night… Sleep tight like a baby!

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