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Edwards 1 Amy Edwards FYS 11/04/2011 Follow Your Dreams Webster’s Dictionary defines a dream as “a series of thoughts, images, or emotions occurring during sleep. Everyone dreams regardless whether they remember them or not. In order to dream, a person must go through several different stages of sleep throughout the night. The five stages of sleep are what allow a person to experience dreams. “The technique of measuring the electrical activity of the brain is call Electro-encephalogram, or EEG” (Cohen 2). This is how scientists determine which stage of sleep a person is in. Before a person can dream, the body must transition from wakefulness to falling asleep. “When a biological clock, in this case the sleep-wake cycle, is set for about 25-hour period it is referred to as the circadian rhythm. Circadian rhythms control the rise and fall of physiological responses such as temperature, and the start and stop of responses like going to sleep and waking up. This rhythm is due to some rhythmical activity of the hypothalamus. When our body is in a state of high arousal, we cannot sleep or we have trouble staying a sleep. Stress, excitement, and drugs that increase arousal can interfere with the onset of sleep as well as staying a sleep” (Gokalp 1). It takes more than wanting to go to sleep to actually be able to fall asleep. A person’s brain must go through a series of steps in order to be able to sleep throughout the entire night. Not only is sleeping a physical process, but a mental and chemical process, too. Edwards 2 “Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons, in the brain. Neurons in the brainstem, which connects the brain with the spinal cord, produce neurotransmitters such as serotonin and norepinephrine that keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin signaling when we fall asleep. These neurons appear to "switch off" the signals that keep us awake. Research also suggests that a chemical called adenosine builds up in our blood while we are awake and causes drowsiness. This chemical gradually breaks down while we sleep” (NIH 3). Once these levels rise high enough, the body and mind become drowsy enough to enter the first stage of sleeping. “The first stage is the lightest stage of sleep and is characterized by drifting in and out of sleep and slow muscle and eye activity. When people are awakened during this phase they usually have fragmented visual memory of what they were experiencing while asleep” (Cohen 2). “Many also experience sudden muscle contractions called hypnic myoclonia, often preceded by a sensation of starting to fall. These sudden movements are similar to the "jump" we make when startled” (NIH 3). Although the body is transitioning from being awake to falling asleep, stage one only lasts “between 1 to 7 minutes”. Once a person falls asleep, the “senses of hearing, touch, taste, sight, and smell no longer function as they do when we are awake” (Cohen 2). Once stage one is completed, our bodies transition into stage two. “The second stage is the one in which the most time is spent, close to fifty percent, during this stage the electrical activity, measured by electrodes, slows down except for infrequent bouts of rapid waves called sleep spindles” (Cohen 2). “In stages 2 through 4 muscle tension, heart rate, respiration, and temperature gradually decline, and it becomes more difficult to be awakened” (Gokalp 1). After stage two, the body begins to enter what’s called deep sleep. Edwards 3 “30 minutes after falling asleep we pass through stage 3 and enter stage 4”. “Activities during the day deplete key factors in our brain and our body that are replenished and repaired by sleep. During stage four sleep, there is a marked secretion of growth hormone, controlling many aspects of metabolism, physical growth, and brain development” (Moorcroft, 1993) (Gokalp 1). “Stages three and four are considered stages of deep sleep; delta waves appear during phase three and are produced almost exclusively during phase four. Delta waves are extremely slow brain waves. Though there is no consistent eye movement or muscle activity during these two periods, they are the phases of sleep when some children experience bedwetting, night terrors, or sleepwalking” (Cohen 2). “It is very difficult to wake someone during stages 3 and 4”. Their bodies are at complete rest. “People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up” (NIH 3). “After this stage we go back to stage 2 and then enter REM sleep, or rapid eye movement sleep” (Gokalp 1). “The discovery of rapid eye movement (REM) sleep suggested that sleep was not, as it was thought to be, a dormant state but rather a mentally dynamic one. Your brain is, in fact, very active in this state, almost to the level at which it is when a person is awake. Yet during this active stage in which most dreams occur, the movements of the rest of the body are completely stilled” (Cohen 2). “We go through this sleep cycle 5-6 times during 8 hours of sleep” (Plotnik, 1993). “A brain-imaging study shows that the neurons in the cerebral cortex become much more active during REM sleep” than the other 4 stages of sleep (Munglani and Jones, 1992). “REM sleep begins with signals from an area at the base of the brain called the pons. These signals travel to a brain region called the thalamus, which relays them to the cerebral cortex – the outer layer of the brain that is responsible for learning, thinking, and organizing information” Edwards 4 (NIH 3). “The cortex can only pass into sleep mode with the help from the thalamus. This is because the thalamus is one of the two structures that make up the diencephalon, the lower part of the fore brain. Its main function in mammals is the relay station of sensory information its way to the cortical center” (Cohen 2). “The pons also sends signals that shut off neurons in the spinal cord, causing temporary paralysis of the limb muscles. Some scientists believe dreams are the cortex's attempt to find meaning in the random signals that it receives during REM sleep. The cortex is the part of the brain that interprets and organizes information from the environment during consciousness. It may be that, given random signals from the pons during REM sleep, the cortex tries to interpret these signals as well, creating a "story" out of fragmented brain activity”. When we switch into REM sleep, our breathing becomes more rapid, irregular and shallow, and our eyes jerk rapidly in various directions. Our heart rate increases, our blood pressure rises, and males can develop penile erections” (NIH 3). “The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. By morning, people spend nearly all their sleep time in stages one, two, and REM” (NIH 3). As you sleep throughout the night, REM sleep increases while deep sleep decreases so that when you wake up, your mind and body feel rested. “The majority of the dreaming that occurs during a sleep cycle occurs during the REM, or paradoxical sleep state. As described above, the brain literally awakens internally during REM sleep. In a person with normal sleep behavior, the REM sleep stage is one of near paralysis for the entire body other than the muscles of the eye and the middle ear. This occurs because of descending inhibition, in which a group of cells in the medulla that descend down the spinal cord and inhibit motor activity” (Cohen 2). Edwards 5 “REM sleep stimulates the brain regions used in learning. This may be important for normal brain development during infancy, which would explain why infants spend nearly half their time sleeping in REM opposed to adults only spending 20 percent of time sleeping in REM. People lose some of the ability to regulate their body temperature during REM, so abnormally hot or cold temperatures in the environment can disrupt this stage of sleep. If our REM sleep is disrupted one night, our bodies don't follow the normal sleep cycle progression the next time we doze off. Instead, we often slip directly into REM sleep and go through extended periods of REM until we "catch up" on this stage of sleep” (NIH 3). “People who are deprived of sleep for one or more days show almost no physical or behavioral changes. However people who are deprived of REM sleep for one or more nights spend more time in REM sleep the next night” (Gokalp 1). There are many factors that can contribute to loss of REM sleep. Many antidepressants suppress REM sleep. Heavy smokers often sleep very lightly and have reduced amounts of REM sleep. They also tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal” (NIH 3). During REM sleep is when we experience vivid dreams. When people wake up during REM sleep, they can often remember their dreams very well. “We typically spend more than 2 hours each night dreaming. Some scientists believe dreams are the cortex's attempt to find meaning in the random signals that it receives during REM sleep. The cortex is the part of the brain that interprets and organizes information from the environment during consciousness. It may be that, given random signals from the pons during REM sleep, the cortex tries to interpret these signals as well, creating a "story" out of fragmented brain activity” (NIH 3). REM dreams are considered to be more perceptual and emotional as opposed to NREM (non-rapid eyemovement) dreams. “Content of NREM dreams is often a recreation of some psychologically Edwards 6 important event. According to Freud, REM dreams are like primary-process thinking which is often unrealistic and emotional, and NREM dreams are like secondary-process thinking which is more realistic” (Franken, 1988). Freud also had a theory that “we dream to satisfy unconscious desires or wishes, especially those involving sex and aggression. If we were to fulfill these wishes during day time it would create too much anxiety. Freud stated that the wishes are represented with symbols (dreams) since they would otherwise be anxiety producing” (Gokalp 1). “Dreams can also be viewed as extensions of waking life, which include thoughts and concerns especially emotional ones. Then, in a sense dreams provide clues to the person's problems, concerns, and emotions” (Plotnik, 1993). Whether dreams come from a person’s subconscious mind or everyday activities, why dreams occur is still a mystery. No one is truly sure of why they happen. Although a person’s mind and body go through five stages of sleep, a person’s mind is never fully at rest. The mind and body never completely stop working. Even after countless studies, scientists are still unable to come up with a direct answer of why dreams occur. However, certain psychologists are able to “define” dreams by using symbols and deep interpretation of thoughts and emotions felt with the dream. Some believe dreams come from the subconscious mind’s deepest wants and needs, while others believe that they are an unrealistic play by play of everyday life. One thing is certain, dreams are inevitable, whatever the reason. Edwards 7 Works Consulted Cohen, Mahalia. Serendip. N.p. 1 April 2008. Web. 1 Nov. 2011. Domhoff, G. William. The Scientific Study of Dreams. Washington, DC: American Psychological Association, 2008. Book. Gokalp, Gokce. California State University, Northridge. N.p. n.d. Web. 1 Nov. 2011. Hartmann, Ernest. The Nature and Functions od Dreaming. New York: Oxford University Press, 2011. Book. Hiroshi Nittono, et al. "Brain Potentials Related To Rapid Eye Movements And Dreaming During REM Sleep: A Short Review Of Psychophysiological Correlates." Sleep & Biological Rhythms 6.3 (2008): 128-138. Academic Search Premier. Web. 3 Nov. 2011. Hobson, J. Allan. “REM Sleep and Dreaming: Towards a Theory of Protoconsciousness”. Nature Reviews Neuroscience 10.22 (2009): 803-813. Academic Search Premier. Web. 1 Nov. 2011. National Institute of Neurological Disorders and Stroke. National Institute of Health. NIH. 21 May 2007. Web. 1 Nov. 2011. Rosen, Marvin. Sleep and Dreaming. Philadelphia: Chelsea House Publishers, 2006. Book. Takeuchi, Tomoka. "Dream Mechanisms: Is REM Sleep Indispensable For Dreaming?." Sleep & Biological Rhythms 3.2 (2005): 56-63. Academic Search Premier. Web. 3 Nov. 2011.