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Chapter 5

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University of Toronto Mississauga
Dax Urbszat

Pages 191 - 231 Chapter 5: Variations in Consciousness The Nature of Consciousness  Consciousness – the awareness of internal and external stimuli  We still have some degree of awareness when we’re asleep or during surgery  William James: created stream of consciousness  our consciousness is continuously changing a) Variations in Awareness and Control  Mind Wandering – refers to people’s experience of task-unrelated thoughts o These thoughts are not related to what they are intentionally trying to do at a given moment o Believed 15%-50% of the time, we are mind wandering o Reduced: if task you are engaged requires significant cognitive resources  The distinction between what we control about our mental processes and what just seems to happen is referred to as the difference between controlled and automatic processes o Controlled: judgements or thoughts that we exert some control over o Autonomic: its effects happen without our intentional control/effort b) Consciousness and Brain Activity  One of best physiological indicators of variations in consciousness  EEG o Records activity from broad swaths of the cortex o Electroencephalograph – a device that monitors the electrical activity of the brain over time by means of recording electrodes attached to surface of scalp o Role: summarizes rhythm of cortical activity in the brain in terms of line tracing  brain waves (vary in amplitude and frequency) o Different patterns of EEG are associated with different states of consciousness (See table on pg 194)  Can’t tell based on measures if changes in mental states causes brain wave rdanges or vice versa.  Some 3 factor could be causing those changes Biological Rhythms and Sleep  Biological Rhythms – are periodic fluctuations in physiological functioning  Ex. the daily alternation of light and darkness, annual pattern of seasons, and phases of the moon a) The Role of Circadian Rhythms  Circadian Rhythms – are 24 hour biological cycles found in humans + species  Role: influences regulation of sleep, produces rhythmic variations in blood pressure, urine production, hormonal secretions etc.  Believed people generally fall asleep as their body temp. begins to drop and awaken as it begins to ascend once again 1 Pages 191 - 231  Can leave individuals physiologically primed to fall asleep most easily at a particular time of day o Varies from person to person depending on their schedules o Each person has an ideal time for going to bed  could promote better quality sleep during the night  To study biological clocks: researchers monitor physiological processes while subjects are cut off from exposure to the cycle of day and night o Result: circadian rhythms generally persist even when external time cues are eliminated o When eliminated, the subject’s cycles run a little longer than normal  When exposed to light, some receptors in the retina send direct inputs to a small structure in hypothalamus  suprachiasmatic nucleus (SCN) o The SCN sends signals to nearby pineal gland  secretes hormone melatonin whose role is adjusting biological clocks  Circadian rhythms in humans  regulated by multiple internal clocks with a central pacemaker located in SCN b) Ignoring Circadian Rhythms  When you ignore your biological clock and sleep at unusual time  quality of your sleep suffers  If you don’t get enough sleep  you accumulate “sleep debt” o For everything to return to normal, must be paid back by getting extra sleep (hour for hour)  Getting out of sync with your circadian rhythms  causes jet lag o You then go to sleep at the wrong time, likely to experience difficulty falling asleep + poor-quality sleep o Result: feel sluggish, fatigue, irritable during day time o People differ in how quickly they can reset their biological clocks o Readjustment process takes about a day for each time  Changes in your normal schedule of 3 hrs + takes several days  Speed of readjustment depends on direction travelled  Easier when you fly westward and lengthen your day than when you fly eastward and shorten your day  Works get less total sleep when they go on rotating shifts c) Melatonin and Circadian Rhythms  Small doses of melatonin  Evidence: can reduce effects of jet lag by helping travellers resynchronize their biological clocks o Researchers: results are inconsistent o When melatonin is used to ameliorate jet lag, the timing of the dose is crucial because calculating the optimal timing is complicated; easy to get wrong  Researchers: tried carefully timed exposure to bright light as a treatment to realign circadian rhythms of rotating shift workers in industrial set 2 Pages 191 - 231 o Pro: can accelerate workers’ adaptation to new sleep-wake schedule, leading to improvements in sleep quality and alertness during work hours o Con: inconsistent + unrealistic option in many work settings  Carefully planning workers’ rotation schedules to reduce severity of their circadian disruption o Pro: reduced if workers move through progressively later starting times and if they have longer periods between shift changes The Sleep and Waking Cycle  Electromyograph (EMG) – records muscular activity and tension  Electroculograph (EOG) – records eye movements  Researcher: observes sleeping subject through a window/video camera from an adjacent room where they also monitor their elaborate physiological recording equipment a) Cycling through the Stages of Sleep 1. Stages 1-4  Sleep is gradual and no obvious transition point between wakefulness and sleep  Length of time it takes people to fall asleep varies considerably; factors:  How long it has been since the person has slept, where the person is in his/her circadian cycle,  Amount of noise/light in sleep environment  Person’s age  Desire to sleep  Boredom level  Recent caffeine or drug intake  Stage 1: brief transitional stage of light sleep that usually lasts only a few (1-7) mins  Breathing + heart rate slow as muscle tension and body temp  Alpha waves that probably dominated EEG activity just before falling asleep give way to lower-frequency EEG activity in which theta waves are prominent  Hynic Jerks – brief muscular contractions that occur as people fall asleep (drowsiness)  As sleeper descends through stages 2,3 and 4  respiration rate, heart rate, muscle tension + body temp continue to  Stage 2: 10-25 mins; brief bursts of higher-frequency brain waves (sleep spindles) appear against a background of mixed EEG activity  Brain waves become higher in amplitude and slower in frequency as body moves into a deeper form of sleep (slow-wave sleep)  Slow-wave sleep consists of stages 3, 4 where high amplitude, low- frequency delta waves become prominent in EEG recordings  Reached in about 30 mins and stay there for 30 mins 3 Pages 191 - 231  Then cycle reverses itself and sleeper gradually moves back upward through the lighter stages 2. REM Sleep  When sleepers reach stage 1 again, they usually go into stage 5  REM sleep (rapid eye movements)  Researchers: use electroculograph to monitor these lateral (side to side) movements that occur beneath sleeper’s closed eyelids  Little ripples move back and forth across person’s closed eyelids  Discovered accidentally after hooking sleep study participants to an apparatus dstigned to measure eye movements  For 1 time: researchers noticed very rapid eye movements at some points during sleep  Thought was an error in machines  so personally observed sleeping participants  “deep” stage  people are relatively hard to awake from it  Irregular breathing, pulse rate, and muscle tone extremely relaxed (as if sleeper virtually paralyzed)  EEG activity is dominated by high-frequency beta waves that resemble those observed when people are alert and awake, low-amplitude brain waves and vivid dreaming  Non-REM (NREM) – sleep consists of sleep stages 1-4 which are marked by an absence of rapid eye movements, relatively little dreaming, and varied EEG activity 3. Repeating the Cycle  During 1 night: people usually repeat sleep cycle about 4 times st  1 REM period  relatively short, lasting only a few minutes  Subsequent REM periods get progressively longer, peaking at around 40-60 minutes in length  NREM intervals tend to get shorter, and descents into NREM stages usually become more shallow b) Age Trends in Sleep  Age alters sleep cycle  Infants: sleep 6-8 times in 24 hour period o 1 few months: spend much more of their sleep time in REM stage than adults do (50% in babies’ sleep; 20% in parents’ sleep) o Then starts to gradually to 30% then to 20%  % of slow-wave sleep and % of time spent in stage 1 increases slightly with these trends stronger in men than women c) Culture and Sleep  Culture  peripheral matters (ex. sleeping arrangements & napping customs)  Co-sleeping – practice of children and parents sleeping together d) The Neural Bases of Sleep 4 Pages 191 - 231  Reticular Formation: important to sleep and wakefulness  Ascending Reticular Activating System (ARAS) – consists of afferent fibres running through the reticular formation that influence physiological arousal o When ascending fibres are cut in brainstem of a cat  continuous sleep  Electrical stimulation along the same pathways produces arousal and alertness  Pones and adjacent areas: critical to generation of REM sleep e) Doing Without: Sleep Deprivation 1. Sleep Restriction  Partial Sleep Deprivation/Sleep Restriction – occurs when people make do with substantially less sleep than normal over a period of time 2. Selective Deprivation  Effects of REM deprivation  Little impact on daytime functioning and task performance  Subject’s pattern of sleeping As the nights go by, it becomes necessary to awake the subjects more and more often to deprive them of their REM sleep b/c they shift into REM more and more frequently rd Ex. took researchers 64 times by 3 night to awaken subjects They spend extra time in REM periods for 1-3 nights to make up for their REM deprivation  Effects of deprivation of slow-wave sleep  As nights go by, more awakenings are required to prevent SWS, and after deprivation of SWS people experience a rebound effect  REM and slow-wave sleep:  Contribute to firming up learning that takes place during the day (memory consolidation)  Promote different types of memory f) Problems in the Night: Sleep Disorders 1. Insomnia  Most common; refers to chronic problems in getting adequate sleep  Occurs in 3 basic patterns: 1) Difficulty in falling asleep initially 2) Difficulty in remaining asleep 3) Persistent early-morning awakening  Difficulty falling asleep  most common in young people  Difficulty staying awake  most common in old people  Associated with daytime fatigue, impaired functioning, an elevated risk for accidents, reduced productivity, depression  Prevalence:  Estimates of prevalence of insomnia vary considerably 5 Pages 191 - 231 Surveys have to depend on respondents’ highly subjective judgement of whether their sleep is adequate Nearly everyone suffers occasional sleep difficulties because of stress, disruptions of biological rhythms  Some people suffer: “pseudo-insomnia” or sleep state misperception  means that they just think they are getting an inadequate amount of sleep in a sleep clinic  Causes:  Excessive anxiety and tension prevent relaxation and keep people awake  Insomnia  side effect of emotional problems: depression, stress  Health problems: back pain, ulcers, and asthma can lead to insomnia  Use of certain drugs  stimulants of cocaine  Treatment:  Most common: prescription of sedative drugs (sleeping pills) Benzodiazepine medications: exert their effects at GABA synapses  most widely prescribed Fairly effective in helping people fall asleep more quickly, + reduce nighttime awakenings + total sleep  Sedatives can be a 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 overdoes in combination with alcohol or oplate drugs There are concerns about people becoming physically dependent on sedatives Gradually becomes less effective  some doses to higher levels creating a vicious circle of escalating dependency and daytime sluggishness Most proportion of time spent in slow-wave sleep and some older drugs can reduce REM sleep 2. Other Sleep Problems  Narcolepsy – a disease marked by sudden and irresistible onsets of sleep during normal waking periods  Person suffering this goes directly from wakefulness into REM sleep usually for a short period of time  Dangerous: some victims fall asleep instantly (ex. while drive)  Causes: some appear to be genetically predisposed to the disease  Treatment: stimulant drugs have been used to treat this condition  Sleep Apnea – involves frequent, reflexive gasping for air that awakens a person and disrupts sleep  Some victims are awakened from their sleep 100s of times a night  Occurs when people literally stop breathing for a min. 10 secs 6 Pages 191 - 231  Accompanied by loud snoring  Often leads to insomnia as a side effect  Treatment: surgery or drug therapy  Nightmares – an anxiety-arousing dreams that lead to awakening, usually from REM sleep  Usually recalls a vivid dream and may have difficulty getting back to sleep  Causes: associated with measures of an individual’s well-being  Higher frequencies of nightmares are associated with increases in scores on variables (ex. state anxiety, depression)  Persistent nightmares  emotional disturbance  Treatment is unnecessary  Night Terrors (Sleep Terrors) – abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic  Can accelerate heart rate  usually occurs during stage 4  Victims usually let out a piercing cry, bolt upright, and then stare into space  Usually don’t recall a coherent dream; remembers simple images  May not indicate an emotional disturbance  Treatment: may not be necessary  often temporary problem  Somnambulism (Sleepwalking) – occurs when a person arises and wanders about while remaining asleep  Tends to occur during 1 2 hours of sleep when individuals are in slow-wave sleep  May last from 15secs – 30 mins  Sleepwalkers may awaken during their journey or may return to bed  Causes: unknown;  Doesn’t appear to cause emotion or psychological problems  Prone to accidents The World of Dreams a) The Contents of Dreams  Tend to unfold in familiar settings with a cast of characters (friends, families)  Several dream types demonstrates gender differences with the affective tone of the dreams differentiating males and females  Dreams associated with males: tend to be positive in nature  Dreams associated with females: tend to
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