Introduction to Psychology

Introduction to Psychology of 97 and occasional dreams. Stage two is characterized by sleep spindles, which are periodic 1-2 second bursts of rapid brain wave activity. Muscles are much more relaxed, breathing and heart rate are slower, dreams may occur and it is harder to awaken. As stage three begins, the brain starts to produce delta waves which appear on an EEG monitor as large, slow waves. Stage 3 is a transition into stage four, which involves stronger, more consistent delta waves. These two stages together are referred to as slow-wave sleep, last about 30 minutes, and are the most difficult from which to awaken. REM Sleep and Dreaming- About an hour after falling asleep, individuals begin to move back into stage 3 and then stage 2. But instead of sliding back into stage 1, people typically move into a 10- minute period of REM (rapid eye movement) sleep. In REM, brain waves are similar to stage 1, but breathing is more rapid and irregular, the heart rate increases, and the eyes dart back and forth underneath closed eyelids. It is usually during REM sleep that people dream. These dreams are prevented frombeing acted out because the brainstemblocks messages from the motor cortex, which leaves the body more or less paralyzed. REM sleep is, in fact, sometimes called paradoxical sleep, because the sleeper appears calm and relaxed despite a great deal of cortical activity. After the REM stage, the sleeper moves back into stage 2 and the next cycle continues. With each cycle, however, periods of REM sleep become longer and periods of stage 4 sleep become shorter. Freud saw dreams as a way to preserve sleep. He suggested that the manifest content of the dream (the images that actually appear to the dreamer) was a disguised version of the dream’s latent content (usually a forbidden sexual or aggressive urge that the dreamer would repress if awake). By distorting or disguising the wish, the dreamer avoids the anxiety that would accompany his awareness of it, and therefore, can remain asleep. According to the activation-synthesis theory, the brain’s neurons fire randomly during sleep, and as we awaken, we construct a dream in order tomake sense out of the random images that have been generated. The information processing theory claims that dreams are a way to consolidate information. As we dream, we sort through the day’s events and stamp them into memory. Functions of Sleep- According to the restoration model, sleep recharges our run down bodies and allows us to recover from physical and mental fatigue. Evolutionary/circadian sleep models emphasize that sleep’s main purpose is to increase a species’ chance of survival in relation to its environmental demands. Activation-synthesis theory views dreaming as the brain’s attempt to fit a story to a random neural activity. Sleep Disorders- Several sleep disorders can interfere with typical sleep patterns. Insomnia refers to chronic difficulty falling asleep, or experiencing restful sleep. Narcolepsy involves extreme daytime sleepiness and sudden, uncontrollable sleep attacks that may last from less than a minute to an hour. REM-sleep behavior disorder (RBD) is where the loss of muscle tone that causes normal REM sleep paralysis is absent. Night terrors are frightening dreams that arouse the sleeper to a near panic state. Nightmares are bad dreams and virtually everyone has them. Sleep apnea is repeatedly stopping and restarting to breathe during sleep. Sleep walking usually occurs during the stage 3 or 4 period of slow wave sleep. Sleepwalkers often stare blankly and are unresponsive to other people. © 2015 Achieve Page 35