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Chapter 5

Chapter 5 Textbook Notes

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Carleton University
PSYC 1001
Elaine Waddington Lamont

Chapter 5 Textbook Notes ● In teens sleep deprivation can put them in risk of emotional difficulties, accidents, cognitive difficulties and psychopathology ● Sufficient sleep seems to be critical to well being. Students better if school start later ● Men tend to get less sleep than women. Full-time work and stress associated with less sleep. People with higher incomes and people who are married/have kids also sleep less ● 1 in 7 canadians report sleep difficulty ● Brain still active while sleeping, therefore we are still conscious while sleeping ● Nature of Consciousness ○ Consciousness - The awareness of internal and external stimuli ○ Maintain some degree of awareness when we are asleep and sometimes even when under anesthesia for surgery ○ Consciousness always changing which is why William James described it as the stream of consciousness ○ Easily able to shift our attention to things of importance/interest in environment ○ Psychologists interested in understanding human behaviour and our behaviour is the result of conscious thought. Also interested in unconscious influences on behaviour. “Almost every human behaviour mixture of (un)conscious processing” ○ Variations in Awareness and Control ■ Although attention and consciousness are closely related, you can have one without the other ■ Mind wandering refers to people’s experience of task-unrelated facts ● People spend ~15-50% of their time mind wandering ● Less likely to occur if task requires significant cognitive resources ● Could be connected to creativity ■ Distinction between what we control and what seems to happen is the difference between controlled and automatic processes ■ Best selling book Blink refers to how quickly and effortlessly some of our judgements and choices seem to be made. Things seem to just happen ○ Unconscious Thought Effects ■ People can make more accurate decisions through unconscious thought (“sleep on it”) ■ Conscious thought is thought without with attention, unconscious thought is thought without attention (attention directed elsewhere) ■ Conscious thought is constrained by capacity limitations, you only consider a small subset of all relevant information when making a decision. ■ Advantage of unconscious thought is that it does not have the same capacity constraints ○ Consciousness and Brain Activity ■ Consciousness arises from activity in distributed networks of neural pathways ■ Scientists use brain imaging methods to explore the link between brain activity and levels of consciousness ● Most commonly used indicator is the EEG, record broad cortex ■ Electroencephalograph (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 ● Summarizes rhythm of cortical activity in the brain in terms of line tracings called brain waves ● Brain-wave tracings vary in amplitude(height), and frequency(cps - cycles per second) ■ Principal Bands of Brain Wave Activity: ● Beta (13-24 cps) - Normal waking thought, alert problem solving ● Alpha (8-12 cps) - Deep relaxation, blank mind, meditation ● Theta (4-7 cps) - Light sleep ● Delta (under 4 cps) - Deep sleep ■ Different patterns of EEG activity are associated with different states of consciousness ■ Measuring brain wave activity maps out the state of consciousness, sleep ● Biological Rhythms and Sleep ○ Important psychological events and processes take place during sleep ○ Important link between sleep quality and the body’s natural rhythm ○ Biological Rhythms - Periodic fluctuations in physiological functioning ○ Organisms have 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 are influential in the regulation of sleep ■ People generally fall asleep as their body temperature begins to drop and awaken as it begins to rise ■ Being a “night person” or “morning person” reflect individual variations in circadian rhythms ■ To study biological clocks, people physiological processes studied while subjects cut off from exposure of day, night, time. ■ Circadian rhythms generally persist even when external time cues are eliminated. However when isolated this way, their cycles run a little longer (~24.2 hours) ■ Exposure of light resets people’s biological clocks ■ When exposed to light, retina receptors send inputs to a small structure in the hypothalamus called the suprachiasmatic nucleus (SCN). The SCN sends signals to the pineal gland which secretes the hormone, melatonin, which plays key role in adjusting biological time clock ■ Human circadian rhythms are regulated by multiple internal clocks, with the central pacemaker located in the SCN ○ Ignoring Circadian Rhythms ■ If you ignore biological clock and go to sleep at unusual times, the quality of your sleep suffers ■ If you get less than the amount of sleep you need, you accumulate “sleep debt”. Sleep debt accumulates and to return to normal, have to pay it back by getting extra sleep. Paid back hour for hour ■ Getting out of sync with circadian rhythms causes jet lag ● Time zone changes but biological clock doesn’t, trouble sleeping ● Jet lag causes you to feel fatigued, sluggish, and irritable. Measurable deficits in cognitive performance ● Time to compensate for jet lag varies by person, but rough estimate is that readjustment depends on direction traveled, ~1 day for every timezone travelled eastward, and ~⅔ day for every time zone travelled westward ● Easier to readjust flying westward (lengthen day) then travelling eastward (shorten day), east-west disparity enough to impact sport team’s performance ■ Biological clock can become out of sync from shift work ■ Lack of sleep or poor quality sleep can increase workers’ accident proneness ■ Canadian shift workers report stress and lower sense of mastery/control ■ Shift working has been linked to higher incidences of physical diseases such as cancer, diabetes, ulcers, high blood pressure, and heart disease ■ Suggest daylight savings time associated with increase traffic accidents ○ Melatonin and Circadian Rhythms ■ Small doses of the hormone melatonin which appears to regulate the human biological clock ■ Suggested melatonin can reduce effects of jet lag by helping travellers resynchronize their biological clocks, but research inconsistent ● To help jet lag, timing of the dose is crucial and easy to get wrong ● Sleep and Waking Cycle ○ Sleep may have some evolutionary significance but debate on how sleep is adaptive (maybe conserve energy, maybe reducing exposure to predators) ○ Also hypothesized sleep might be adaptive because it helps animals restore bodily resources depleted by walking activities ○ People sleeping experience quite a bit of physical and mental activity throughout the night ○ In sleep labs, in addition to an EEG, both EMG and EOG are also used ■ Electromyograph (EMG) - Records muscular activity and tension ■ Electrooculograph (EOG) - Records eye movements ○ Cycling Through the Stages of Sleep ■ There are rhythms evident within the experience of sleep itself ■ During sleep people cycle through a series of five stages ■ Stages 1-4: ● How long it takes to fall asleep depends on how long it has been since the person last slept, where they are on the circadian cycle, amount of noise or light in the sleep environment, person’s age, desire to fall asleep, last caffeine intake, stress level, boredom, etc ● Stage 1 sleep is a brief transitional stage of light sleep that usually lasts a few minutes (1-7 min.). Breathing and heart rate slow as muscle tension and temperature decline. The alpha waves that dominate the EEG while awake, give way to lower frequency theta waves. Brief muscle contractions known as hypnic jerks occur ● As sleeper goes through stages 2, 3, 4 the respiration rate, heart rate, muscle tension, and body temperature continue to decline ● Stage 2 lasts 10-25 minutes. Brief bursts of higher-frequency brain waves, called sleep spindles, appear against background of mixed EEG activity. Maybe important for consolidation of motor tasks ● Gradually brain waves slow in frequency, enter deeper sleep called slow wave sleep ● Stages 3 and 4 make up slow wave sleep (SWS) where high amplitude, low frequency delta waves become prominent in EEG ● Takes about ½ an hour to reach slow wave sleep and remain there for another ½ hour ● Cycle reverses itself and sleeper moves upward through cycles ■ REM Sleep ● When people get back to what should be stage 1 again, they go through a fifth stage known as REM (Rapid Eye Movements) sleep ● In sleep labs electrooculograph used to measure side to side movements of eyes beneath eyelids ● REM sleep is a “deep” stage of sleep that is hard to awaken from ● During REM sleep, irregular breathing and pulse rate. ● Muscle tone is extremely relaxed so sleeper paralyzed almost and doesn’t move much ● Although REM is deep sleep, EEG activity dominated by high frequency beta waves that that resemble those when awake ○ Related to association between REM sleep and dreaming ● Dreams are more frequent, vivid, and memorable during REM sleep but also occur during non-REM sleep ■ REM Sleep - A relatively deep stage of sleep marked by rapid eye movements, high frequency and low amplitude brain waves, and vivid dreaming ■ Non-REM Sleep - Consists of stages 1 through 4 which are marked by an absence of rapid eye movements, relatively little dreaming, and varied EEG activity ○ Repeating the Cycle ■ People usually repeat sleep cycle 4 times a night ■ First REM period is relatively short (few minutes). Subsequent REM periods get progressively longer peaking at 40-60 minutes ■ NREM stages tend to get shorter and descents into NREM stages become more shallow ■ Most slow-wave sleep occurs early in the sleep cycle, and REM sleep piles up in the second ½ of the sleep cycle ○ Age Trends in Sleep ■ Sleep cycle of babies immediately after birth is simple, only REM and NREM sleep. Newborns will sleep 6-8 times a day, totaling 16 hours. Newborns spend most time in REM sleep, 50% of sleep compared to 20% of sleep in adults ■ During rest of first year, babies time spent in REM sleep drops to 30% ● Continues to decrease until levels off at 20% ■ Through adulthood REM sleep time remained the same (~20%), SWS declines and and % spent in stage 1 increases slightly ● Shift toward lighter sleep contributes to frequency of awakenings ● Total average sleep time also declines with advancing age ■ Older adults show more sleepiness during the day than younger adults ■ Older adults more difficulty adapting to circadian phase shifts, ex. jet lag ■ Sleep complaints elevate with age but mainly from health problems, not just from turning old itself ○ Culture and Sleep ■ Psychological and physiological experience of sleep doesn’t vary across cultures ■ Are different sleeping arrangements and nap customs for different cultures such as kids sleeping with parents ○ Neural Bases of Sleep ■ Rhythm of sleep and waking is regulated by subcortical structures. One important structure is the reticular formation in brainstem ■ Ascending Reticular Activating System (ARAS) - Consists of the afferent fibres running through the reticular formation that influence physiological arousal ■ The ARAS projects diffusely into the main cortex areas ● When ascending fibres are cut in the brainstem of a cat, results in continuous sleep ○ Electrical stimulation along same pathway produces arousal and alertness ■ Activity in the pons and adjacent areas of the midbrain critical to generation of REM sleep ■ Various areas of hypothalamus regulate sleep and wakefulness ■ Sleep and waking is regulated through a constellation of interacting brain cells ○ Sleep Deprivation ■ Ignoring our internal clock may put our physical and psychological health at risk ■ Sleep Restriction ● Partial Sleep Deprivation/Sleep Restriction occurs when people make due with substantially less sleep than normal over a period ● Result of people trying to squeeze more hours out of their day ● Negative effects seen when person has to work long, difficult, or a dull job or when sleeping less than 5 hours for many nights ● People who are sleep deprived often feel their performance is fine even though their cognitive function is clearly impaired ● Sleep deprived people are bad at predicting if and when they’ll fall asleep, which is why tired truck drivers don’t pull over when should ● Many major disasters (Chernobyl, Challenger, etc) due to lapses in judgement and attention due to sleep deprivation ● Increased irritability when sleep deprived ● Sleep is important to regulate our emotional life during our waking hours ○ Study found that amygdalas of sleep deprived people were significantly more active to negative photos. These amygdalas showed less connectivity to rest of brain structures associated with prefrontal control. In all, more emotional reactivity and less control in response to negative stimuli ■ Selective Deprivation ● Selective Deprivation occurs when people get enough NREM sleep but deprived of REM sleep ○ Has little impact on daily functioning, but does affect subjects sleeping patterns, they spontaneously shift into REM sleep more and more frequently ○ When the sleep without interruption, they spend extra time in REM sleep to make up for the REM deprivation ○ Same deprivation and “rebound effect” seen with SWS ● Selective deprivation shows there are specific needs for REM and SWS. Each thought to promote different types of memory, and to firm up what was learned during day, memory consolidation ○ New creative insights to what was learned ○ Representation of memories in brain will be enhanced ● Sleep fosters the process of neurogenesis - Formation of new neurons ■ Sleep Loss and Health ● Sleep restriction triggers hormonal changes that increase hunger ● Link between short sleep duration and obesity ● Sleep loss impairs the immune system and increases inflammatory responses ● Links between short sleep duration and diabetes, hypertension, and cardiovascular disease ● Sleeping less than 7 hours but also surprisingly sleeping over ten hours, increase mortality ○ Sleep Disorders ■ 78 different types ■ Insomnia ● The most common sleep disorder ● Insomnia - Chronic problems in getting adequate sleep ● 3 Basic Patterns: ○ 1.) Difficulty in falling asleep initially ○ 2.) Difficulty in remaining asleep ○ 3.) Persistent early morning awakenings ● Pattern 1 most common in young people, while 2 and 3 more common in middle-aged and elderly ● Results in: daytime fatigue, less productive, risk of accidents, depression, anxiety, substance abuse, hypertension, & health problems ● Prevalence ○ Everyone suffers occasional sleep loss from stress, etc ■ Clear up spontaneously ○ Prevalence of insomnia increases with age and is 50% more common in women ○ Sleep State Misperception - “Pseudo-Insomnia”. Only think they’re not getting enough sleep, but are ○ Many people underestimate the amount of sleep they get ● Causes ○ Excessive anxiety and tension cause people not to be able to relax and fall asleep ○ Frequently side effect of emotional problems (stress, pressure, work) ○ Can be caused by problems like back pain, ulcers, asthma ○ Certain drugs especially stimulants ○ according to hyperarousal model some people show hormonal patterns that fuel arousal, high heart rate, high metabolism, high body temp.
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