Sleep is defined as the regular state of natural rest observed in all mammals, birds and fish. Sleep is not actually "unconsciousness," but rather, it is a natural state of rest characterized by a reduction in voluntary body movement and decreased awareness of the surroundings. But, what is the importance of sleeping? What purposes does it serve besides time for the body to be inactive? Some experts believe that sleep is a period in which the brain figures out problems, arranges data, and restores chemical imbalances within the body. After sleeping material learned the day before is better understood and retained. During sleep the brain produces more hormones, especially the growth hormone, and the subcontious is more active during sleep than the contious. It is commonly believed that the normal person needs about eight hours of sleep per night. However, some people can be completely restored after only six hours and other need nine for complete rest.
Another commonly held view is that the amount of sleep one requires decreases as one ages, but this is not necessarily the case. The ability to sleep, rather than the need for sleep, appears to decrease when people get older. Sleep experts also believe that you cannot "store" sleep by sleeping more on the weekends in preparation for the normal work week. Night-shift workers produce less melatonin, a hormone which not only promotes sleep but has been shown to have cancer-prevention benefits as well. Despite the risks, sleeping less is attractive to some because of the additional time made available, and many people feel they have to sleep less to maintain their lifestyle. Lack of sleep can affect your lifestyle, depending on how old you are and what you do. Students tend to retain material and understand it better the more they sleep.