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Chapter 5

Chapter 5 - variations in consciousness.docx

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York University
PSYC 1010
Rebecca Jubis

Chapter 5 - Variations in consciousness Nature of consciousness Variations in awareness and control  Mind wandering – thoughts that are not related to what they are intentionally trying to do at a given moment.  Mind wandering less likely to occur if the task you are engaged in is one that requires significant cognitive resource Consciousness and brain activity  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  rhythm of cortical activity in the brain in terms of line tracings called brain waves  Amplitude = height, frequency = cycles per period Biological rhythms and sleep Biological rhythms – periodic fluctuations in physiological functioning  internal biological clocks that somehow monitor the passage of time Role of circadian rhythms  Circadian rhythms – 24-hour biological cycles found in humans and many other species  Circadian rhythms can leave individuals physiologically primed to fall asleep most easily at a particular time of the day  People tend to fall asleep as their body temperature begins to drop and awaken as it begins to ascend once again Ignoring circadian rhythms  When slept at an unusual time, the quality of sleep suffers  If you lack sleep you develop “sleep debt” and every hour must be paid back.  And it can also cause jet lag  Flying westward = easier to adapt to jet lag, flying eastward = harder to adapt to jet lag Melatonin and circadian rhythms  Hormone melatonin can reduce the effects of jet lag by helping travelers resynchronize their biological clocks  but timing is crucial and it is easy to get it wrong. Sleep and waking cycle  Electromyograph (EMG) – records muscular activity and tension  Electrooculograph (EOG) – records eye movements Cycling through the stages of sleep Stages 1-4 Stage 1  light sleep (1-7min)  Breathing and heart rate slow as muscle tension and body temperature decline  Hypnic jerks – brief muscular contractions that occur as people fall asleep Stages 2,3, &4  Respiration rate, heart rate, muscle tension and body temperature continue to decline.  Stage 2 has sleep spindles (brief bursts of higher-frequency brain waves)  Gradually brain waves become higher in amplitude and slow in frequency  Slow-wave sleep (SWS) – consist of sleep stages 3 and 4, during which high- amplitude, low-frequency delta waves become prominent in EEG recordings  then the cycle reverses itself and the sleeper gradually moves back upward through the lighter stages REM (rapid eye movement) sleep  When sleeper reaches stage 1 once again, it is considered 5 stage of sleep, REM sleep.  Hard to wake people up, muscle tone is extremely relaxed  REM sleep is the deepest sleep BUT the EEG activity is like the one when someone is alert and awake.  REM sleep = dreaming (dreams that are easy to remember)  REM sleep – relatively deep stage of sleep marked by rapid eye movements; high frequency, low amplitude brain waves, and vivid dreaming  Non-REM sleep – sleep stages 1-4, which are marked by an absence of rapid eye movements, relatively little dreaming, and varied EEG activity Repeating the cycle  People usually repeat the sleep cycle about 4 times  REM sleep get longer progressively  NREM sleep gets shorter progressively Age trends in sleep  Babies have longer REM sleep (50%) and adults have 20% of REM sleep  Older = less sleeping period Culture and sleep  Co-sleeping – practice of children and parents sleeping together  varies around different cultures  Naps vary in cultures The neural bases of sleep  Brain structure that is important to sleep and wakefulness is the reticular formation in the core of the brainstem  Ascending reticular activating system (ARAS) – consists of the afferent fibres running through the reticular formation that influence physiological arousal  when ascending fibres are cut, the result is continuous sleep & electrical stimulation produces arousal and alertness  Sleep depends on the interplay of many neural centres and neurotransmitters Doing without: sleep deprivation Sleep restriction  Partial sleep deprivation AKA sleep restriction – when people make do with substantially less sleep than normal over a period of time.  Sleep deprivation causes poor cognition but effort, concentration, and performance is higher than normal sleeping people Selective deprivation  Deprivation of a stage of sleep  example. REM sleep  Has little impact on task performance  Subjects fall into REM sleep more quickly when deprived of REM sleep  Rebound effect – spend extra time in REM period for 1-3 nights to make up for their REM deprivation or any stage in sleep  REM and slow-wave sleep each promote different types of memory  Memory consolidation – effect of firming up learning that has taken place during the day Problems in the night: sleep disorders Insomnia  Insomnia – chronic problems in getting adequate sleep  3 basic patterns o difficulty in falling asleep (most common and in young adults) o difficulty in remaining asleep (common in older people) o persistent early-morning awakening (common in older people)  daytime fatigue, impaired functioning, risk for accidents, reduced productivity, depression  50% more common in women than in men  treatments: sedative drugs  too dependent on drugs cause long-term side effects, and the medication gets weaker leading to overdose. OR behavioral treatments Other sleep problems  Narcolepsy –disease marked by sudden and irresistible onsets of sleep during normal waking periods o Falling directly to REM sleep  accidents!  Sleep apnea – frequent, reflexive gasping for air that awakens a person and disrupts sleep  when a person stops breathing for about 10 seconds o Heart failure  Nightmares – anxiety arousing dreams that lead to awakening, usually from REM sleep o Persistent nightmares may reflect on emotional disturbance o Can recall dream  Night terrors AKA “sleep terrors” – abrupt awakenings from NREM sleep, accompanies by intense automatic arousal and feelings of panic o Usually in stage 4 o Heart rate acceleration o Cannot recall dream o Can fall asleep again easier  Somnambulism AKA sleep walking – when person arises and wanders
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