What is Sleep?

What is Sleep?

Sleep is defined as a state where our body stops being active in terms of motor activity and sensory perception. During sleep, our brains are partially conscious, capable of only limited but necessary functions. Our muscle movements also become involuntary during this stage. Basically, it is the state that the body enters when it is in need of rest. Sleep has been a popular subject of study over the years and there have been several perspectives formed about it through the ages. It is said that the Greek philosopher, Aristotle, was one of the first people to make a scientific observation about sleeping because he defined sleep as “a seizure of the primary sense-organ, rendering it unable to actualize its powers, arising of necessity ... for the sake of its conservation.” Plato believed that sleep occurred when vapors from the stomach rose up and moved towards the brain, blocking its pores.

The ancient Egyptians were also known to have made observations about the sates of sleep and dreaming. They would analyze symbols and meanings behind their dreams and consider them as prophecies from the Gods. The first known study of the sleep-wake cycle or ‘Circadian Rhythm’ dates all the way back to 1772, when a Frenchgeo-physicist, going by the name of Jean-Jacques d'Ortous de Mairan observed biological rhythms by conducting a circadian experiment. His curiosity and inspiration came from observing a heliotrope plant. He noticed that the leaves of the plant would open during the day and close during the night. 

He assumed that this was a result of the plant being in the presence of sunlight. But, in order to make sure, he conducted an experiment by keeping the plant in total darkness. He noticed that the leaves continued the same behavior even in the absence of sunlight. This led him to make the conclusion that the plant had an internal clock which regulated its functions. His observation eventually went on to inspire further studies in the area of ‘Chronobiology’.

In the 19th century, physicians actually believed that sleep occurred as a result of blood flow being stopped to the brain. Despite all these studies and observation, there is still a lot that we do not know about sleep. However, it cannot be denied that sleep is an extremely important function of the human body. It is so important, that our survival depends on it.