You do that daily (or rather nightly), but most likely you don’t appreciate its importance. Sleeping. One of the most important things you need to live. And I mean you really need it. In a really good quality and quantity. This is a quick tutorial regarding sleeping its importance and quality. In a nutshell.
In this article, I will have a closer look at sleep. This everyday or rather every night intuitively repeated ritual and its quality have a significant impact on our life and wellbeing.
What is sleep?
Cambridge dictionary defines sleep as ‘the resting state in which the body is not active, and the mind is unconscious’.  Also, MedicineNet says that sleep is a compound process of restoration and reparation for the body . Although we all sleep and go to bed in the night, intuitively, without even thinking about it, scientists still don’t have a clear answer why we do it and what is the biological purpose of it. [3, 4] Despite this uncertainty, we all know that for sure, we will not be able to function properly without sleep. Therefore, in this article, I will talk a bit more about it, why do we need it and how to improve its quality.
Why do we need to sleep?
One of Harvard’s scientists, Dr J. Allan Hobson, joked once that ‘The only known function of sleep is to cure sleepiness’.  He was right, but that’s not the entire truth. Sleep affects several brain and body functions. During it, your brain removes toxins build up while you’re awake.  In regards to the body, it helps it to regenerate, build and repair new tissue and recharge your immune system and your heart and cardiovascular system.  That’s in a nutshell. But along with the exploration of sleep and it reasons scientists came up with a few theories which explain in more depth why we sleep.
- Inactivity theory
It’s one of the earliest theories about sleep. It’s called the adaptive evolutionary theory and it suggests that the inactive state of the body in the night is an adaptation that served survival functions. Its purpose was to keep organisms out of danger during these periods by staying still and quiet. It was a protective mechanism that allows survival in the darkness, which slowly evolved to become what we now call sleep. 
- Energy Conservation Theory
Of course, for the majority of us living in wealthy nations food scarce isn’t a problem. But not always life was so easy for the humankind. The theory of energy conservation comes from the time when our ancestors needed to hunt for food, which never was a sure thing when they would have their next meal or survive long periods without it. This is how scientists explain why we’ve developed sleep, to conserve energy to allow us to survive. [7, 8]
- Restorative Theories
This theory says that sleep is a relief of bodily or cerebral deficiency caused by our awakening activity. However, as convenient as it sounds, it has been undermined. Since scientists have discovered that during sleep, our brain isn’t completely inactive (and, in fact, it stays very active). It’s been proven that during sleep we experience REM sleep called rapid eye movement sleep  (I will explain both in more depth in the chapter about phases of sleep) during which our brain is active and our eyes move rapidly. 
- Brain Plasticity Theory
Brain plasticity is simply the brain’s ability to adapt and change in consequence of what we experience.  It suggests the sleep might be involved in this process. However, the theory of brain plasticity has been researched for years on a large number of human and animals. Still, the evidence of it remains unsystematized. 
As you can see, modern science can explain quite a few reasons why we sleep, but to answer the simple ‘why?’ questions still aren’t that easy.