What is Circadian Rhythm? Why sleeping for at least seven hours is important

A man sleeps on a bench in a park. Image: Reuters.

It is often said that every person should sleep for at least seven hours a day to keep the body and mind healthy. Have you ever wondered why? Or what would happen if you do not sleep enough? We explain the reason behind the body going in an unconscious state every night.

The human body follows biological clock called the Circadian Rhythm.  This body clock responds to the outside light, and when it is dark, the body produces melatonin at night. Melatonin is a hormone secreted by the pineal gland which inhibits melanin formation and is thought to be concerned with regulating the reproductive cycle. The body only produces melatonin when it's dark and stop production when it senses light.

What you would be surprised to know is that the body divides sleep into four stages and performs them multiple times. The first two stages are called a Non-Rapid Eye Movement or light sleep mode where the body makes a transition from being awake to falling asleep. During this process, heart-rate and breathing slow down and the body temperature drops. 

The third stage is known as Delta Sleep where delta brain waves are released. It is the first stage of deep sleep where growth hormones are produced by the cells for bones and muscles which are used by the body to repair itself. The last stage is where the body begins to dream. The body produces chemicals that temporarily paralyses the body. When in this state, the human body does not act the dreams through actions, which is why the body enters into this paralysis mode. Although the body is paralysed, the brain is highly active, and the eyes roll back and forth, which is why this state is known as Rapid Eye Movement Sleep. 

The reason why the human body should at least sleep seven hours a day is that if the body does not get enough rest, it can lead to chronic conditions like obesity, diabetes or heart diseases that could shorten life expectancy. The human body in its lifetime, on an average needs, to sleep for a total of 25-30 years or roughly one-third of its life. So next time you think of sleeping less, think about it.