Scientifically reviewed by Team

Written by


She would be a morning person if mornings started at noon. Art historian, taurus, coffee lover, traveler, F1 fan who hates to drive, and well experienced insomniac with one life goal, to sleep like a coala for up to 20 hours per day.

Defining Sleep

People were always intrigued by the condition of sleep and tried to find out what happens to our body while we are sleeping.

If you would have to define sleep, how would you describe it? Is it a need, urge, satisfaction, inevitable waste of time or something else? We all experience it, but we also treat it differently, depending on our habits and priorities.

What is sleep and why do we sleep? What are dreams? What happens when we fall asleep? Those and many other similar questions have been current since the beginning of time. People were always intrigued by the condition of sleep and tried to find out what happens to our body while we are sleeping. In today’s post, we are going to explore the mysteries of sleep by going way back into the past to see how sleep was perceived in ancient times and to check some medical definitions of sleeping.


Sleep in Ancient Times

Since the Egyptians are the oldest civilization in history, we decided to start from them, from the very beginning. The Egyptians used hieroglyphics, a pictorial letter, so let’s check how they presented sleep. They used a combination of two words/signs, the word qed was depicted as a bed, and it denotes sleep, and the other word is resut which means to come awake, shown as an open eye which represents the dream. Combining symbols of bed and open eye, we get an expression awaken with sleep, which corresponds to the early descriptions of similarity between dreams and wakefulness.

Ancient Egyptians believed that every person has five bodies, and they also thought that the soul (ba) could go away from our physical body during sleep. In that way, sleep was in some aspect considered similar to death, since they believed in the afterlife, for them death meant that the person went to a different world. Sleep was one of the ways to reach that mysterious other world and communicate with people who have passed away. They had an idea that the deceased was sleeping, so they thought about their tombs as houses and their chamber rooms as bedrooms.

Just like many other cultures, Egyptians were fascinated by dreams, and they believed that the gods were sending them messages through dreams, to help them make decisions, cure an illness or to guide them through life. Egyptians also had a dream book, a book in which all possible dreams were described and interpreted; one of them is kept in the British Museum in London. Interpretation of some dreams varies from one culture to another, so it interesting to see how did they describe them according to their culture.

The ancient Egyptian medicine was also aware of sleep disorders, which is an interesting fact since their medicine is one of the oldest documented scientific disciplines. Many healing rituals, diets, and even surgical treatments were described on papyrus. On one of the found papyri, it was explained how ancient Egyptians used poppy seeds as a hypnotic which relieves symptoms of headache and insomnia, but also how it was used as an anesthetic. In some other papyrus, Egyptians recommended a herb called Thyme, as an excellent cure that can reduce snoring. It is clear that the ancient Egyptians knew more than a few things about sleep medicine, but many mysteries and secrets of sleep and Egyptian people are yet to be discovered.

If we move forward in time, to the period of ancient Greece, we can see that sleep was also one of their preoccupations. Famous Greek philosopher, Aristotle, even wrote a small treatise On sleep, around 350 B.C., in which he discusses three stages of sleep. But besides him, many other theories about sleep and dreams were written by ancient Greek poets such as Homer, Pindar or Hesiod. Greek philosophers turned sleep and dreams into a part of their philosophical researches, pre-Socratic philosophers like Democritus and Heraclitus proposed a theory about the naturalistic origin of sleep and dreams. On the other hand, Pythagoras claimed that dreams have a divine origin. That makes it clear that sleep was always a fascination of many scientists and philosophers as some phenomenon.


Medical Definition of Sleep

When it comes to the medical point of view, sleep represents the body’s natural rest cycle. Sleep cycles are different stages of sleep through which we all go through around five times each night while sleeping. One sleep cycle can last from 90 to 120 minutes, and it represents our progress from NREM stages to the final REM sleep phase, the first cycle during the night is the shortest one, and it lasts around 90 minutes, others last at least 100 minutes. During the state of sleep, an increased brain activity occurs, brain cells work slower but with much higher intensity. It has been estimated that we spend ⅓ of our lives sleeping, so just this fact shows us how important sleep is.

Every night almost all of us experience for hours this state of unconsciousness while we are resting. About 80% of our sleep time is dreamless, and this phase is known as non-REM (non-rapid eye movement) sleep. While at the NREM stage, our body pressure, heart rate, and breathing are low and regular, and our body is relatively still. The sleep cycle has four stages:


Sleep Cycle Length by Age

Since our age dictates our needs and lifestyle, the amount of sleep that we require for normal functioning also changes as we age.


What Happens While We Sleep?

Although when we are sleeping we barely move or consciously do anything, our body is actively restoring and working, so now we are going to check through which processes our body is undergoing while we are snoozing.



Sleep Related

Was this post helpful?

Leave a Reply

Your email address will not be published.