Sleep was considered a block of time when you are not awake; it is now known that sleep has distinctive stages that cycle throughout the night. Your brain is active throughout sleep, but different things happen during each stage. A number of vital tasks are carried out during sleep to maintain good health and enable people to function at their best.

Because of this, insufficient sleep can be unhealthy and even dangerous. One of the first systems affected by lack of sleep is the immune system. Too little sleep damages immune function and makes us vulnerable to illnesses. Hence, adequate sleep is required for truly healthy immune function. Another organ negatively impacted by too little sleep is the liver. The liver is the largest of the internal organs and has over 500 functions in the body. One is regulating the energy level one will have for the next day so that staying up late and not sleeping long enough impairs the liver's ability to do this and other jobs.

It is said that a person requires at least eight hours of sound sleep. After a days work the body needs to rest in order to restore the damages occurred during the day. The liver itself does over 500 different specific functions one of the most important being cleaning the blood. There is lot of chemicals now in air, water and food; because of this the liver is being overburdened to clean up everything which is another function of the liver. Thus we see that liver does many different functions during the day and so there is the need for the body to shut down and sleep to repair itself. Some people sleep less than eight hours. However research done on sleep has shown that the brain needs to have at least three hours to shut down, for it to kind of reset the cycle.

But to do all the repair work, it takes a lot longer than three hours. If one is sleeping only for three hours for more than one night then the effect is as good as no sleep at all, because the body becomes tired as it has not got the chance to repair itself. One would feel like that of being hit with a ton of bricks. Here the body is screaming for help. It needs sleep so that it can rejuvenate itself. It will be saying that it didn't get the chance to kind of catch up on all the sleep the night before and they have all these other things that they needed to repair from the days before and now they have all these other things that we are making them do today. So may be the brain continues to work even if you sleep for three to four hours a day but in the long run if you're not getting, close to eight hours a night, it eventually will take a heavy toll on the brain.

So it is better always to get at least eight hours of sleep everyday. There are certain things which we have to keep in mind to prevent colds and other things of that nature. The first thing is that your immune system has to be very strong. And we all know that our immune system is constantly being attacked from outside invaders like bacteria, virus and different types of chemicals. If you get enough sleep it will do a world of good for your liver which will eventually help to build a good immune system.