How Many Hours Sleep Do We Need Daily?

According to Professor Jim A. Horne, a leading researcher affiliated to the Sleep Research Centre at the Department of Human Sciences at Loughborough University in England, a leisurely snooze on a Sunday morning does not amount to anything, as it makes no sense to stay up all night or sleep late at night on the weekdays.

Lack of sleep is an open invitation to various health risks including depression and stress and leaves you feeling groggy and irritable the next day. Hence, people who do not get their full quota of sleep at night are usually bound to be unproductive and cannot get too much work done the next day. Working on the night shift is not an excuse to become an insomniac.
An adult person ideally needs six to eight hours of sleep everyday. People who smoke, eat or drink too much, do not get enough exercise or generally neglect their health tend to adopt a casual approach towards their sleep as well. In fact, Napoleon Bonaparte, the exiled French general, once said something to this effect, but of course, in a lighter vein: a man should ideally get about six hours of sleep, a woman should try to sleep for about seven hours and a fool should sleep for about eight hours.

Sleep, as we know, is important to us because it helps restore tired organs and tissues in our body. But how much sleep do we actually need?
For most of us, eight hours seems to be about the right amount. Yet we know that there are a great many people who get along perfectly with less sleep and some who may even need more. A great deal depends on the way we live. But a good general rule to follow is to sleep as long as we have to in order to feel happy and be able to work at our best when we awaken.
There are actually different levels of sleep. There is a deep sleep and a shallow sleep. In a shallow sleep, our body does not get the same kind of rest it gets in a deep sleep, so that after eight hours of a shallow sleep we may still feel tired- But a short, deep sleep can be very restful.
Alexander the Great was able to get a deep sleep whenever he needed it. Once, during the night before an important battle, he remained awake longer than anyone else. Then he wrapped himself in a cloak and lay down on the earth. He slept so deeply that his generals had to wake him three times to give the command to attack!
Normally when we go to sleep, our "sleep centre" blocks off nerves so that both our brain and our body go to sleep. One prevents us from wanting to do anything, and the other makes our internal organs and limbs go to sleep. But sometimes only one goes to sleep and the other does not. A very tired soldier can sometimes fall asleep (brain sleep) and keep on marching, because his body is not asleep!