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Dax Urbszat (643)
Chapter 5

PSY100 Notes-Chapter 5.docx

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University of Toronto Mississauga
Dax Urbszat

Chapter 5  Consciousness is the awareness of internal and external stimuli  Consciousness is continually changing, stream of consciousness (William James)  Mind-Wandering refers to people’s experience of task-unrealted thoughts  Consciousness doesn’t arise from any distinct structure in the brain, but from activity in distributed networks of neural pathways  EEG is a device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp  Human brain-waves are divided into four principal bands: EEG Pattern Frequency (cps) Typical State Beta 13-24 Normal walking though, alert problem solving Alpha 8-12 Deep relaxation, blank mind, meditation Theta 4-7 Light sleep Delta Under 4 Deep Sleep  Our degree of intentional control over cognitive processes varies. Controlled processes are those over which we have intentional control while automatic processes occur without our intention  Brain waves vary in frequency(cps) and amplitude  Discovery of Rapid Eye Movement(REM) and the realization by William Dement of the significance of dreams fueled scientific research on sleep  Stanford was the first university that had a lab dedicated to sleep research  Variations in consciousness are shaped in part by biological rhythms  Biological Rhythms are periodic fluctuations in physiological functioning  Circadian Rhythms are the 24-hour biological cycles found in humans and many other species, these are influential in the regulation of sleep o Daily cycles also produce rhythmic variations in BP, urine production, hormonal secretions and other physical functions  Studies show that people generally fall asleep as their body temperature decreases, and awaken as it increases  Circadian rhythms can leave individuals psychologically primed to fall asleep most easily at a particular time of the day  Biological Clocks: when exposed to light, some receptors on the retina send direct inputs to a small structure in the hypothalmus called the suprachiasmatic nucleus (SCN), the SCN sends signals to the nearby pineal gland, whose secretion of hormone melatonin plays a key role in adjusting biological clocks.  If one ignores circadian rhythms and sleeps whenever, the quality of sleep suffers  Getting less than the amount of sleep needed causes a sleep debt. The sleep debt accumulates and for everything to return to normal, it must be paid back by getting extra sleep.  Jet lag = ignoring the circadian rhythm, when you travel you sleep at “night-time” in that country, this makes one fatigued  Readjustment is easier when you travel westward and lengthen you day, and harder when travelling east and shortening the day  To help people follow their biological clock, scientists suggest giving melatonin, the hormone that regulates the biological clock  Some studies show that melatonin helps to reduce the effects of jet lag but the results are inconsistent Sleeping Cycles  Sleepers experience physical and mental activity throughout the night  To test sleeping habits, individuals are hooked up to an EEG, EMG-which records muscular activity and tension, and EOG which records eye movement  Five stages of sleep: o Stages 1 to 4:  The onset of sleep is gradual, there is no obvious transition between wakefulness and sleep  The length of time it takes a person to fall asleep depends on:  How long it has been since they slept  Where the person is in their circadian cycle  Amount of noise and light in the environment  Age  Desirability to fall asleep  Boredom Level  Stress Level  Recent caffeine/ drug intake  Stage 1: is a brief transitional stage of light sleep that only lasts 1-7 minutes. o Breathing and heart rate slow as muscle tension and body temp. decrease. o Go from dominant alpha waves to lower frequency EEG activity in which theta waves are prominent. o Hypnic Jerks- brief muscular contraction occur as people fall asleep  Stage 2 o Respiration rate, heart rate, muscle tension and body temperature continue to decline o In stage 2 (10-25 minutes), brief bursts of higher-frequency brain waves, called sleep spindles, appear against a background of mixed EEG activity o Slowly, brain waves become higher in amplitude and slower in frequency as the body moves into a deeper form of sleep called, slow-wave sleep  Stages 3 & 4 o Slow-wave sleep: consists of these two stages, during which high-amplitude, low frequency delta waves become prominent. o Respiration rate, heart rate, muscle tension and body temperature continue to decline o Individuals reach slow-wave sleep in ½ hour and stay there for 30 minutes  After this, the cycle reverses itself and the sleep gradually moves back upward through the lighter stages Rem Sleep th  When sleeps reach stage 1 again, they usually go into the 5 stage of sleep known as REM sleep  REM means rapid eye movement which is prominent in this stage  Lateral(side to side) movements that happen beneath the sleeper’s closed eye lids. Can be seen if observed, little ripples move back and forth across the person’s closed eye lids  Discovered accidentally in the 1950s in Nathaniel Kleitman’s lab  A deep stage of sleep that people are relatively hard to awaken from it  also marked by irregular breathing and pulse rate  muscle tone is extremely relaxed, bodily movements are minimal and the sleeper is virtually paralyzed  Although it is a very deep stage of sleep, EEG activity is dominated by high- frequency beta waves that resemble those observed when people are awake  That is probably due to dreaming which occurs in the REM stage  Although REM dreams are more frequent, vivid and memorable, dreaming does occur in non-REM sleep  Smith’s research suggests that brain activity during sleep is central to consolidation of information acquired throughout the day  Also suggests that different stages of sleep may be implicated in memory for different types of tasks or info  REM sleep is a relatively deep stage of sleep marked by rapid eye movements; high-frequency, low amplitude brain waves; and vivid dreaming  Non-Rem Stages are stages 1 to 4 marked by the absence of rapid eye movement, relatively little dreaming and varied EEG activity. Repeating the Cycle  During the course of the night, the cycle is repeated about four times.  As the night goes on the cycle changes gradually, the first REM period is relatively short, lasting only a few minutes.  Subsequent REM periods get longer, peaking around 40-60 minutes in length  NREM intervals tend to get shorter and descent into the NREM usually become more shallow  Most slow-wave sleep occurs early in the cycle  REM sleep tends to pile up in the second half of the cycle  Young adults spend 15-20% of their time of slow-wave sleep, 20-25% in REM Age Trends in Sleep  Babies only have REM sleep and NREM sleep, they spend much more time in REM stage that adults do (50% to 20%) for the first six months  After the REM sleep decreases to 30%, it keeps decreasing until it levels of at 20%  Elders need less sleep that teens, older adults deal with sleep impairment more easily than young people Culture and Sleep  Co-sleeping  Napping The Neural Bases of Sleep  One brain structure that is important to sleep and wakefulness is the reticulat formation in the core of the brainstem  Ascending Reticular Activating System(ARAS) consists of the afferent fibres running though the reticular formation that influence physiological arousal  Activity in the pons and adjacent midbrain seems to be critical to the generation of REM sleep Sleep Deprivation  Partial sleep deprivation or sleep restriction, which occurs when people make- do with less sleep than normal over a period of time  Sleep deprivation equals to poor performance on cognitive tasks  Sleep is important to regulate our emotional life when awake, there is more emotional reactivity and less control in sleep deprived individuals  When waking someone from REM sleep constantly, they tend to spontaneously shift to REM more and more frequently  When REM-deprivation experiments come to an end, the subjects spend extra time in REM periods for one to three nights  Same thing happens with slow-wave sleep  Sleep seems to enhance memory of specific learning activities that occurred during the day  REM sleep seems to help n
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