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Department
Psychology
Course
PSYC 1010
Professor
All Professors
Semester
Winter

Description
Chapter 5: Variations in Consciousness KEY POINTS IN THIS CHAPTER (pages 182-183) - William James emphasizes that consciousness is a continually changing stream of mental activity. Consciousness varies along a continuum of levels of awareness. - Consciousness may have evolved because it allowed humans to think through the possible consequences of their actions and avoid some negative consequences. People maintain some degree of awareness during sleep and sometimes while under anaesthesia. - Brain waves vary in amplitude and frequency (cps) and are divided into four bands: beta, alpha, theta, and delta. Variations in consciousness are related to variations in brain activity, as measured by the EEG. The Nature of Consciousness - consciousness - the awareness of internal and external stimuli - includes” - awareness of external events - awareness of internal sensations - awareness of self as the unique being having these experiences - awareness of thoughts about these experiences - contents of your consciousness are continually changing - William James called this the stream of consciouness Variations in Levels of Awareness - William James emphasizes that consciousness is a continually changing stream of mental activity - Sigmund Freud wanted to examine what went on beneath the surface of the stream of mental activity - consciousness varies along a continuum of levels of awareness - research has shown that people continue to maintain some awareness during sleep and even when they are put under anaesthesia for surgery - research indicates that while people are asleep they remain aware of external events to some degree - Consciousness may have evolved because it allowed humans to think through the possible consequences of their actions and avoid some negative consequences. Consciousness and Brain Activity - consciousness arises from activity in distributed networks of neural pathways - electroencephalograph (EEG) - a device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp - summarizes the rhythm of cortical activity in the brain in terms of line tracings called brain waves --> vary in amplitude (height) and frequency (cycles per second (cps)) --> human brain-wave activity is usually divided into four principle bands based on the frequency of the brain waves: beta (13-24 cps), alpha (8-12 cps), theta (4-7 cps), delta (under 4 cps) Chapter 5: Variations in Consciousness - Variations in consciousness are related to variations in brain activity, as measured by the EEG - We do not know whether changes in mental states cause brain wave changes or vice versa based on measures of correlations - it could also be that some third factor such as signals from a subcortical structure in the brain is causing both KEY POINTS IN THIS CHAPTER (pages 183-185) - The cycle of sleep and wakefulness is influenced considerably by circadian rhythms. Exposure to light resets biological clocks by affecting the activity of the suprachiasmatic nucleus and the pineal gland, which secretes the hormone meltonin - Ignoring your biological clock by going to sleep at an unusual time may have a negative effect on your sleep. Being out of sync with circadian rhythms is one reason for jet lag and for the unpleasant nature of rotating shift work. - Melatonin may have value in efforts to alleviate the effects of jet lag and it may be an effective sedative in some situations Biological Rhythms and Sleep - variations in consciousness are shaped in part by biological rhythms - periodic fluctuations in physiological functioning - existence of these rhythms means that organisms have internal “biological clocks” that somehow monitor the passage of time The Role of Circadian Rhythms - Circadian rhythms - the 24-hour biological cycles found in humans and many other species - particularly influential in the regulations of sleep in humans - also produce rhythmic variations in blood pressure, urine production, hormonal secretions, and other physical functions, as well as alertness, short-term memory, and other aspects of cognitive performance --> research has led investigators to conclude that circadian rhythms can leave individuals physiologically primed to fall asleep most easily at a particular time of day (optimal time varies from person to person) - Sleep quality may be more strongly correlated with health and well-being than quantity - Studies have shown thata circadian rhythms generally persist even when external time cues are elimintated Chapter 5: Variations in Consciousness - Exposure to light resets biological clocks - receptors in the retina send direct inputs to a small structure in the hypothalamus called the the suprachiasmatic nucleus (SCN) which sends signals to the nearby pineal gland, which secretes the hormone melatonin Ignoring Circadian Rhythms - Ignoring your biological clock by going to sleep at an unusual time may have a negative effect on your sleep. - Being out of sync with circadian rhythms is one reason for jet lag - people differn in how quicly they can reset their biological clocks to compensate for jet lag but takes approximately a day for each time zone crossed - speed of readjusting depends on the direction travelled - generally easier to travel west and lengthen day than to travel east and shorten day. - Being out of sync with circadian rhythms is one reason for the unpleasant nature of rotating shift work - studies show that workers get less total sleep and poorer-quality sleep when they go on rotating shifts - can increase accident proneness and mental and physical health Melatonin and Circadian Rhythms - giving small doses of the hormone melatonin appears to regulate the human biological clock - evidence from a number of studies suggests that malatonin can reduce the effects of jet lag by helping travellers resynchronize their biological clocks - May be an effective sedative in some situation - can facilitate daytime naps but may have limited value in the treatment of night time insomnia KEY POINTS IN THIS CHAPTER (pages 186-190) - Research on sleep is typically done in laboratories where volunteers come to spend the night. Participants are hooked up to an EEG, EOG, EMG, and instruments that monitor heart rate, respiration, pulse rate, and body temperature - When people fall asleep, they evolve through a series of stages in cycles of approximately 90 minutes. Slow-wave sleep consists of stages 3 and 4, during which delta waves are prominent. During the REM stage, sleepers experience rapid eye movements, brain waves that are characteristic of waking thought, and vivid dreaming. The sleep cycle tends to be repeated about four times a night, as REM sleep gradually becomes more predominant and NREM sleep dwindles. - The REM portion of sleep declines during childhood, levelling off at around 20%. During adulthood, slow-wave sleep declines. Total sleep time decreases from most elderly people, although it increases fro some. Culture appears to have little impact on the physiological experience of sleep but it does influence napping patterns and sleeping arrangements, such as co-sleeping. - The neural bases of sleep are complex. Arousal depends on activity in the ascending reticular activating system, but a constellation of brain structures and neurotransmitters contribute to regulation of the sleep and waking cycle. Chapter 5: Variations in Consciousness The Sleep and Waking Cycle - Sleepers experience quite a bit of physical and mental activity throughout the night - Research on sleep is typically done in laboratories where volunteers come to spend the night. - Participants are hooked up to an EEG, EOG, EMG, and instruments that monitor heart rate, respiration, pulse rate, and body temperature - electromyograph (EMG) - records muscular activity and tension - electrooculograph (EOG) - records eye movements Cycling through the Stages of Sleep - During sleep, people cycle through a series of five stages STAGES 1-4 - onset of sleep is gradual and there is no obvious transition point between wakefulness and sleep - length of time taken to fall asleep varies depending on on many factors - including how long it has been since the person has slept, where the person is in his or her circadian cycle, the amount of noise or light in the sleep environement, and the personʼs age, desire to fall asleep, boredom level, recent caffeine or drug intake, and stress level, among other things - stage 1 is a brief transitional stage of light sleep that usually last only a few (1-7) minutes - breathing & heart rate slow as muscle tension and body temperature decline - alpha waves that probably dominate d EEG actibity jsut before falling asleep five way to lower-frequency EEG activity in which theta waves are prominent - hypnic jerks - brief muscular contractions that occur as people fall asleep - generally occur during stage 1 drowsiness - As sleep descends through stages 2,3,and 4 of the cycle, respiration rate, hear rate, muscle tension and body temperature continue to decline - stage 2 - lasts about 10-25 minutes - brief bursts of higher-frequency brain waves, called sleep spindles, appear against the background of mixed EEG activity - Gradually, brain waves become higher in amplitude and slower in frequency, as the body moves into slow-wave sleep (SWS) - consists of sleep stages 3 and 4, during which high-amplitude, low-frequency delta waves become prominent in EEG recordings - typically reach SWS in about 30 minutes and stay there for ~30 minutes - Then cycle reverses itself and the sleeper gradually moves back upward through the lighter stages REM SLEEP - when sleepers reach what should be stage 1 again, they usually go into the fifth stage of sleep - rapid eye movements (REM) sleep - REM sleep - a relatively deep stage of sleep marked by rapid eye movements, high frequency, low -amplitude brain waves, and vivid dreaming - REM stage tends to be a “deep” stage of sleep in the conventional sense that people are relatively hard to awaken from it Chapter 5: Variations in Consciousness - marked by irregular breathing and pulse rate - muscle tone is extremely relaxed - so much so that bodily movements are minimal and the sleeper is virtually paralysed - Although REM is a relatively deep stage of sleep, EEG activity is dominated by high- frequency beta waves that resemble those observed when people are alert and awake - probably related to dreaming - most dream reports come from the REM stage - REM dreams tend to be more frequent, vivid and memorable but there is evidence to suggest that mentation or dreaming does occur in non-REM sleep periods too - interest in examining whether recall of dreams from both REM an non-REM sleep is explained better by assuming the existence of a single dream generator or two different dream generators - research - examining the relations between brain functioning in sleep and memory - suggests that brain activity during sleep is central to consolidation of information acquired during the day --> different stages of sleep may be implicated in memory for different types of tasks or information - may be that different types of sleep are important for different types of learning - Non-REM (NREM) sleep - consists of sleep stages 1 through 4 which are marked by an absence of rapid eye movements, relatively little dreaming and varied EEG activity REPEATING THE CYCLE - The sleep cycle tends to be repeated about four times a night, as REM sleep gradually becomes more predominant and NREM sleep dwindles - Most slow-wave sleep occurs early in the sleep cycle and REM sleep tends to pile up in the second half of the sleep cycle Age Trend in Sleep - Age alters the sleep cycle - Newborns will sleep six to eight times in a 24-hour period, often exceeding a total of 16 hours of sleep - in the first few months, REM accounts for about 50% of babiesʼ sleep as compared to 20% of adultsʼ sleep - The REM portion of sleep declines during childhood, levelling off at around 20%. - During adulthood, slow-wave sleep declines. - Total sleep time decreases for most elderly people, although it increases for some. Culture and Sleep - Culture appears to have little impact on the physiological experience of sleep - disparities in sleep are limited to more peripheral matters such as sleeping arrangements and napping customs (ex: co-sleeping (practice of children and parents sleeping together) The Neural Bases of Sleep - rhythm of sleep and waking appears to be regulated by subcortical structures that lie deep within the brain Chapter 5: Variations in Consciousness - one brain structure that is important to sleep and wakefulness is the reticular formation in the core of the brainstem - The ascending reticular activating system (ARAS) - consists of the afferent fibres running through the reticular formation that influence physiological arousal - Although the ARAS contributes to the neural regulation of sleep and waking, the ebb and flow of sleep and waking is regulated through activity in a constellation of interacting brain centres - neurotransmitters also contribute to regulation of the sleep and waking cycle - Therefore, no single structure in the brain serves as a :sleep centre” nor does any one transmitter serve as a “sleep chemical” - sleep depends on the interplay of many neural centres and neurotransmitters KEY POINTS IN THIS CHAPTER (pages 191-196) - The effects of sleep deprivation depend on a variety of factors. Our Featured Study showed that college students underestimate the impact of sleep deprivation. Increased sleepiness can be a significant problem that appears to contribute to many transportation accidents and mishaps at work. Research on selective sleep deprivation suggests that people need REM sleep and slow-wave sleep. - Many people are troubled by sleep disorders. Insomnia has a variety of causes. Sleeping pills generally are a poor solution. The optimal treatment for insomnia depends on its apparent cause - Narcolepsy is a disease marked by sudden, irresistible onsets of sleep during normal waking periods. Sleep apnea involves frequent gasping for air, which occurs when people stop breathing. Night terrors are abrupt awakenings from NREM sleep accompanied by panic, whereas nightmares are anxiety-arousing dreams that typically awaken one from REM sleep. Somnambulism typically occurs during slow-wave sleep. Doing without: Sleep Deprivation COMPLETE DEPRIVATION - complete deprivation of sleep has negative effects on participantsʼ mood and on their performance on both cognitive and perceptual-motor tasks - tend to be modest and many researchers hae been impressed by how well sleep- deprived subjects can perform if they are motivated to do so PARTIAL DEPRIVATION - sleep restriction - occurs when people make do with substantially less sleep than normal over a period of time - studies suggest that the effects depend on the amount of sleep lost and on the nature of the task at hand - negative effects are most likely when subjects are asked to work on long lasting, difficult, or monotonous tasks, or when subjects are asked to restrict their sleep to under 5 hours for many nights - Studies indicate that partial sleep deprivation can impair individualsʼ attention, reaction time, motor coordination, and decision making Chapter 5: Variations in Consciousness SELECTIVE DEPRIVATION - type of partial sleep deprivation - REM deprivation - evidence indicates that it has little impact on daytime functioning and task performance, but does have some interesting effects on subjectsʼ patterns of sleeping - begin to shift into REM more and more frequently - after REM-deprivation, subjects tend to experience a “rebound effect” where they spend extra time in REM period to make up for the REM deprivation - similar results observed when subjects deprived of slow-wave sleep - conclude that people must have specific needs for REM and slow-wave sleep Problems in the Nights: Sleep Disorders INSOMNIA - insomnia - chronic problems in getting adequate sleep - Occurs in three basic patterns: - difficulty in falling asleep initially - difficulty in remaining asleep - persistent early-morning awakening - associated with daytime fatigue, impaired functioning, and elevated risk for accidents, reduced productivity, absenteeism at work, depression, and increased health problems Prevalence - The prevalence of insomnia increases with age and is about 50% more common in women than in men - some people may suffer from “psudo-insomnia” or sleep state misperception - they think they are getting an inadequte amount of sleep - Many people underestimate how much sleepp they get Causes - has many causes - excessive anxiety and tension, emotional problems, significant stress, health problems, use of certain drugs (especially stimulants) Treatment - Most common approach to the treatment of insomnia is prescription of sedative drugs (sleeping pills) -->Poor long-term solution - have carryover effects that can make people drowsy and sluggish the next day and can lead to memory decrements - can cause an overdose in combination with alcohol or opiate drugs - Because of the bodyʼs ability to develop tolerance to drugs, using sedative routinely to “cure” insomnia can lead to a vicious circle of escalating dependency as large and larger doses of the sedative are needed to produce the same effect - some of the older drugs decrease the proportion of sleep in slow-wave sleep or REM sleep - Melatonin Chapter 5: Variations in Consciousness - sedatives do have an impotant place in the treatment of insomnia, but they need to be used cautiously and conservatively - Treatment programs based on psychology have also been shown to be useful - relaxation procedures and behavioural interventions --> cognitive behavioural therapy (CBT) OTHER SLEEP PROBLEMS - Narcolepsy - a disease marked by sudden and irresistible onsets of sleep during normal waking periods - person goes directly from wakefulness to REM sleep usually for a short period of time (10-20 minutes) - cause unclear, possible genetic predisposition, stimulant drugs have modest effect on treating - Sleep apnea - involves frequent, reflexive gasping for air that awakens a person adn disrupts sleep - stops breathing for a min of 10 seconds - may be treated with surgery or drug therapy - Nightmares - anxiety-arousing dreams that lead to awakening usually from REM sleep - found significant correlations between number of nightmares and measures of well- being, including neuroticism, trait anxiety, state anxiety, and depression - counselling may prove helpful - Night terrors (sleep terrors) - abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic - accelerations of heart rate - usually occur during stage 4 sleep early in the night - panic usually fades quickly and return to sleep is fairly easy - not indicative of an emotional disturbance - Somnambulism (sleep walking) - occurs when a person arises and wanders about while remaining asleep - usually tends to occur during the first two hours of sleep when individuals are in slow- wave sleep - cause unknown although appears to have a genetic predisposit
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