Sleep, Dreams, and Our Mental and Physical Processes
Scientists have been researching and conducting studies to discover the true meaning of sleep and dreams. Scientists have developed a few theories on whether we sleep and dream to build up our mental or physical energy.
According to the author of an article in Encarta Encyclopedia, Siegel defined sleep as the "natural state of rest characterized by reduced body movement and decreased awareness of surroundings" (Siegel). In an article on MSNBC Interactive, scientists believe in the physical aspects such that energy is lost throughout the day, so sleep is a time to build or restore that energy back up for the next day. The body also does some repair work. A hormone is released while sleeping to restore and build body tissue (Why do we need").
Other scientists in the MSNBC article argue that sleep restores our mental energy. Humans spend all day using the brain and draining out the energy, so sleep is the time to boost that energy up again ("Why do we need"). The National Institute of Neurological Disorders and Strokes explained that sleep is also needed for the nervous system to work properly. Sleep gives neurons the chance to shut down and repair themselves, if they do not rest then they begin to malfunction. In deep sleep, growth hormones are released into body, which is important for children and young adults ("Brain Basics"). The true function of sleep though still remains a mystery.
Whether sleep is a time for mental or physical restoration, the process of sleep is the same. Lefton, author of a well-known textbook called Psychology, explains that sleep is broken down into five stages. By using electroencephalograms (EEGs), scientists found out more about these five stages. Electrodes are placed on the forehead and the scalp to create graphic records of brain activity. Rapid eye movement (REM) is a stage of sleep. It is high frequency, waves per second, low amplitude, height of waves, and lots of eye movement. This stage does not happen until four stages of non-rapid eye movement (NREM) occur. During an eight-hour sleep period, people go through five full cycles of the five stages. Each stage lasts about ninety minutes each (Lefton, 195).
In stage one, a person is in a light sleep and can be awakened easily. The brain waves have a low amplitude and a fast frequency. In stage two, the waves have a low amplitude and "non-rhythmic brain activity." In stage two is a slight bit deeper sleep that stage one. Stage three, delta waves have a slower frequency and a high amplitude. Stage four is a person’s deepest state of sleep (Lefton, 196).
The fifth stage is REM sleep. Breathing and heart rate increase, eyes begin to move rapidly, high frequency and low amplitude waves occur (Lefton, 196). REM sleep is affected by chemical stimulation of melatonin, chemical that helps one sleep, to pons in the brainstem (Siegel). REM is an important part of brain development; this is why...