Human beings often underestimate the importance of sleep in their lives. Contrary to popular belief, sleep is not a passive phenomenon. It is a dynamic process during which the body recharges, recovers and recuperates. Several physiological systems of the body undergo repair while we sleep. Thus, sleep deprivation can lead to serious health implications.
According to the National Sleep Foundation in the United States, human infants require as much as sixteen hours of sleep, while human adults require about eight to nine hours of sleep every night. Women in the first 3 months of pregnancy often need several more hours of sleep than usual. The amount of sleep a person needs also increases if he or she has been deprived of sleep in previous days. Sleep is particularly important for the brain. Even 24 hours of continuous wakefulness can lead to reduced memory and concentration ability, hallucination and mood swings.
Precisely how sleep affects human beings is still an area of intense research. Scientists are still trying to comprehend the molecular and physiological functioning of the body in the sleeping stage. But studies conducted so far have only reiterated that sleep is essential for survival. One such study conducted on rats revealed that sleep deprived rats had a severely shortened life span and a breakdown in the immune system. The normal life span of rats is 2-3 years, however sleep deprived rats live for only 3 weeks. These rats develop abnormal low body temperatures and sores on their tails and paws. (Mostaghimi, 2005)
Researches conducted over the ages have theorised about the possible functions of sleep. As mentioned earlier, healing and repair are two of the key functions of sleep. A study conducted revealed that sleep hastened the healing process of burn wounds in rats. (Gumustekin et al, 2004) Sleep also forms an important means of energy conservation especially when a person is ill. This probably happens because cytokines, chemicals our immune systems produce while fighting an infection, are powerful sleep-inducing chemicals. Sleep may help the body conserve energy and other resources that the immune system needs to mount an attack. The body is in a quiescent stage while sleeping and considerably less energy is spent in the physiological functioning of the body. Sleep might also be an anabolic state marked by physiological processes of growth and rejuvenation of the organism's immune, nervous, muscular, and skeletal systems (with some exceptions). When a person is in deep sleep, growth hormones are released in the body. Also, proteins, which form the building blocks of the body, are produced in large numbers during sleep.
The most important function underway in a sleeping human being is memory processing. Scientists have successfully correlated sleep to memory. Sleep helps the brain commit new information to memory through a process called memory consolidation. More specifically, working memory was shown to be adversely affected by sleep deprivation. Working memory keeps information active for further processing and supports higher-level cognitive functions such as decision making, reasoning, and episodic memory. (Turner, 2007)
Stages of Sleep
A human being usually passes through five stages of sleep. The first four stages can be