Everyone sleeps, but there is a major mystery about sleep; why do we do it? In ancient and prehistoric times, when animals roamed the wild, it doesn't seem ideal to sleep. The Greek philosopher Aristotle proposed the first scientific theory about why we sleep. He believed that a person wakes up after the digestion of food is complete (2013). This theory has been proven false, but research shows that sleep has effects on the brain and body. Humans sleep for about a third of their lives and there are dozens of different theories as to why this is actually a necessity (TED, 2013). Three theories stand out. They include: restoration, energy conservation, brain processing and memory consolidation. We think of the restoration theory that we replace and rebuild while we sleep. Energy consolidation equates to the simple loss of calories while we sleep. Brain processing and memory consolidation is the theory that scientists believe the brain processes information and builds memory. This theory is one that many scientists lean towards more than others. Sleep is more beneficial for the brain than the body, but sleep is beneficial for a person's health. A person deprived of sleep is more likely to contract diseases, including cardiovascular disease and cancer (Cox, 2002). In the 1950s, the average amount of sleep a person got was 8 hours. The average amount of time people sleep is now 6.5 hours (TED, 2013). It is important that people continue to sleep to ensure brain plasticity. Brain plasticity is the natural way the brain changes. The brain is constantly working, even during sleep. Rapid eye movement (REM) sleep...... middle of paper ...... Scientists can give an electrical impulse to a pair of neurons, and they will communicate more easily in the future. This action is known as long-term potentiation (LTP). This effect will last long enough to create a memory. LTP is widespread in the hippocampus. The hippocampus is a subcortical structure that stores new information in the brain's memory banks. In the waking brain, information about the outside world reaches the hippocampus via the entorhinal cortex (Buzsák, 1998). During sleep, the direction of information flow is reversed: population surges initiated in the hippocampus invade the neocortex. We suggest that neocortico-hippocampal information transfer and the process of modification of neocortical circuits by hippocampal output occur in a temporally discontinuous manner associated with the sleep-wake cycle...