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Chapter 5

Chapter 5- Body Rhythms and Mental States.docx

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Department
Psychology
Course
PS101
Professor
Lawrence Murphy
Semester
Fall

Description
Body Rhythms and Mental States  Consciousness: awareness of oneself and the environment Biological Rhythms: The Tides of Experience  Biological Rhythm: a periodic, more or less regular fluctuation in a biological system; may or may not have psychological implications  Biological clock in brains governs waxing and waning of hormone levels, urine volume, blood pressure, and even the responsiveness of brain cells to stimulation  Entrainment: the synchronization of biological rhythms with external cues, such as fluctuations in daylight  Endogenous: generated from within rather than by external cues  Circadian Rhythm: a biological rhythm with a period (from peak to peak or trough to trough) of about 24 hours; from the Latin circa, “about” and dies, “a day” o Best-known circadian rhythm is the sleep-wake cycle, but there are hundreds of others that affect physiology and performance  Ex. Body temperature fluctuates about one degree centigrade each day, peaking, on average, in the late afternoon and hitting a low point, or tough in the wee hours of the morning  Seasonal rhythms common. Birds migrate south in fall, bears hibernate in winter, and marine animals become active or inactive depending on bimonthly changes in tides  In humans, female menstrual cycle occurs every 28 days on average  Biological rhythms influence everything from the effectiveness of medicines taken at different times of day to alertness and performance on job  With better understanding of internal tempos, may be able to design out days to take better advantage of our bodies’ natural tempos Circadian Rhythms  Exist in plants, animals, insects, and humans  Reflect adaptation of organisms to many changes associated with rotation of Earth on axis such as changes in light, air pressure, and temperature  External time cues abound, and people's circadian rhythms become entrained to them, following strict 24-hour schedule  To identify endogenous rhythms, scientists must isolate volunteers from sunlight, clocks, environmental sounds, and all other cues to time o Some have spent weeks or even months alone in caves and salt mines, linked to outside world by one-way phone line and cable transmitting physiological measurements to surface o Now volunteers live in specially designed rooms equipped with stereo systems, comfortable furniture, and temperature controls o When participants have been allowed to sleep, eat, and work whenever they wished, few have lived a “day” that is much shorter or longer than 24 hours. If allowed to take daytime naps however, most participants live a day that averages about 24.3 hours  Commonly entrained to external time cues  Endogenous rhythm averages around 24.3 hrs  Removed from cues about 10% of people have clocks running slower and 10% running faster  Increase in accidents at transition to daylight Saving Time The Body’s Clock  Suprachiasmatic Nucleus (SCN): an area of the brain containing a biological clock that governs circadian rhythms o Located in tiny teardrop-shaped cluster of cells in hypothalamus o Neural pathways from special receptors in back of eye transmit information to SCN and allow it to respond to changes in light and dark. SCN then sends out messages that cause brain and body to adapt to changes  Other clocks exist but SCN regarded as master pacemaker  Melatonin: a hormone, secreted by the pineal gland, that is involved in the regulation of daily biological (circadian) rhythms o When sleep in darkened room, melatonin level rises, when wake up to lightened room, melatonin falls  Melatonin therapy used to treat insomnia and synchronize disturbed sleep-wake cycles of blind people who lack light perception and whose melatonin production doesn’t cycle normally When the Clock is Out of Sync  Internal Desynchronization: a state in which biological rhythms are not in phase (synchronized) with one another o Often occurs when people take airplane flights across several time zones o Sleep and wake patterns adjust quickly but temperature and hormone cycles can take several days o Jet lag affects energy level, mental skills, and motor coordination  Occurs when worker must adjust to new shift. Efficiency drops, person tired and irritable, accidents become more likely, sleep and digestive disorders may occur  May become matter of life and death for cops, emergency room personnel, airline pilots, truck drivers, and operators of nuclear power plants  University of British Columbia research Stanley Coren studied records of all accidental deaths in the US over a three-year period, found that the spring shift to daylight saving time (and the minimal sleep loss associated with it) produced short-term increase in likelihood of accidental death but the fall shift had little effect  Rotating night-shift assignments don’t allow worker’s circadian rhythms do resynchronize, can help resynchronize by using melatonin or other techniques, not ready however o Best approach is to avoid shifting as much as possible  Circadian rhythms not perfectly regular in daily life. Can be affected by illness, stress, fatigue, excitement, exercise, drugs, mealtimes, and ordinary daily experiences. Even diet  Circadian rhythms differ greatly from individual to individual because of genetics Moods and Long-Term Rhythms  Ecclesiastes “To everything there is a season, and a time for every purpose under the heaven.” Does the Season Affect Moods?  Some people become depressed during particular seasons, typically winter, when periods of daylight are short- known as seasonal affective disorder (SAD)  During winter months, SAD patients report feelings of sadness, lethargy, drowsiness, and a craving for carbs  To counter effects of sunless days, physicians and therapists have been treating SAD patients with phototherapy, having them sit in front of bright fluorescent lights at specific times of the day, usually early in the morning. Also prescribing antidepressants and other drugs  Approx. 2-3% of Canadian population suffers from SAD, US is less than 1% same with Europe, Asian is 0-1%  Much more common in women, ratio about 2:1  When people with SAD exposed to either a brief period (about 30 minutes) of bright light after waking or to light that slowly became brighter, simulating dawn, their symptoms were reduced  Concluded that SAD patients must have some abnormality in the way they produce or respond to melatonin  One study, SAD patients produced melatonin for about half an hour longer at night in winter than summer whereas control subjects showed no season pattern Does the Menstrual Cycle Affect Moods?  First half, increase in estrogen causes lining of uterus to thicken in preparation for possible pregnancy. Mid-cycle, ovaries release mature egg, or ovum. After, ovarian sac that contained egg begins to produce progesterone- helps prepare uterine lining to receive egg. Then, if conception doesn’t occur, estrogen and progesterone levels fall, uterine lining sloughs off as the menstrual flow and cycle begins again  Question is whether these physical changes are correlated with emotional or intellectual changes as folklore and tradition would have us believe  Most people think so, physical symptoms (fatigue, headache, irritability, and depression) associated with the days preceding menstruation came to be thought of as an illness and was given the label: “premenstrual syndrome” (PMS). Since then, most people have assumed, uncritically, that many women “suffer” from PMS or its supposedly more extreme and debilitating version, “premenstrual dysphoric disorder” (PMDD)  What does evidence actually show? Many women have physical symptoms associated with menstruation, including cramps, breast tenderness, and water retention although women vary tremendously. Physical symptoms can just make women grumpy or unhappy just as pain can make men grumpy or unhappy  But emotional symptoms associated with menstruation (notably irritability and depression) are pretty rare  Just like with SAD patients, more people claim to have symptoms than actually do  In reality, fewer than 5% of all women have such symptoms predictably over their cycles  Consciousness is the awareness of oneself and the environment. Changing states of consciousness are often associated with biological rhythms- periodic fluctuations in physiological functioning. These rhythms are typical entrained (synchronized) to external cues, but many are also endogenous, generated from within even in the absence of time cues. Circadian fluctuations occur about once a day; other rhythms occur less frequently or more.  When people live in isolation from all time cues, they tend to live a day that is just slightly longer than 24 hours. Circadian rhythms are governed by a biological “clock” in the Suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN regulates, and in turn is affected by, the hormone melatonin, which responds to changes in light and dark and which increases during the dark hours. When a person’s normal routine changes, the person may experience internal Desynchronization, in which the usual circadian rhythms are thrown out of phase with one another. The result may be fatigue, mental inefficiency, and an increased risk of accidents  Folklore holds that moods follow long-term biological rhythms. Some people do show a recurrence of depression every winter, in a pattern that has been labelled seasonal affective disorder (SAD), but serious seasonal depression is rare. The causes of SAD are not yet clear, but may involve an abnormality in the secretion of melatonin. Light treatments can be effective  Another long-term rhythm is the menstrual cycle, during which various hormone levels rise and fall. Well-controlled double-blind studies on “PMS” do not support claims that emotional symptoms are reliably and universally tied to the menstrual cycle. Overall, women and men do not differ in the emotional symptoms they report or in the number of mood swings they experience over the course of a month  Expectations and learning affect how both sexes interpret bodily and emotional changes. Few people of either sex are likely to undergo dramatic monthly mood swings or personality changes because of hormones The Rhythms of Sleep  Christopher Evans “The behaviour patterns involved in sleep are glaringly, almost insanely, at odds with common sense.” The Realms of Sleep  Not much was known about changes that occur in brain during sleep until early 1950s in lab of physiologist Nathaniel Kleitman who was the only person in the world at the time who had spent his entire career studying sleep o Kleitman had given his grad student Eugene Aserinsky the task of finding out whether the slow, rolling eye movements that characterize the onset of sleep continue throughout the night o Found eye movements occur but they were rapid, not slow. Using electroencephalography (EEG), these researchers including another of Kleitman’s students William Dement were able to correlate the rapid eye movements with changes in sleepers’ brain-wave patterns  Rapid Eye Movement (REM) sleep: sleep periods characterized by eye movement, loss of muscle tone, and dreaming  Periods of REM sleep alternate with periods of fewer eye movements, non-REM (NREM) sleep, in cycle that recurs every 90 minutes or so  REM periods last from a few minutes to as long as an hour, average about 20 minutes  Non-REM periods divided into distinct stages, each associated with particular brain-wave pattern  When you first climb into bed, close your eyes, and relax, your brain emits bursts of alpha waves  Alpha waves have regular, slow rhythm and high amplitude (height). Gradually, waves slow down even further, and drift into the Land of Nod, passing through four stages, each deeper than the previous o Stage 1. Your brain waves become small and irregular, and you feel yourself drifting on the edge of consciousness, in a state of light sleep. If awakened, you may recall fantasies or a few visual images o Stage 2. Your brain emits occasional short bursts of rapid, high-peaking waves called sleep spindles. Minor noises probably won't disturb you o Stage 3. In addition to the waves that are characteristic of stage 2, your brain occasionally emits delta waves, very slow waves with very high peaks. Your breathing and pulse have slowed down, your muscles are relaxed, and you are hard to rouse o Stage 4. Delta waves have now largely taken over, and you are in deep sleep. It will probably take vigorous shaking or a loud noise to awaken you. Oddly, though, if you walk in your sleep, this is when you are likely to do so. No one yet knows what causes sleepwalking, which occurs more often in children than adults, but it seems to involve unusual patterns of delta-wave brain activity  Sequence takes 30-45 minutes then you move back up the ladder from 4-1. At this point, bout 70-90 minutes after onset of sleep, something peculiar happens  Stage 1 doesn’t turn into drowsy wakefulness, as one might suspect. Instead, your brain begins to emit long bursts of very rapid, somewhat irregular waves. Heart rate increases, blood pressure rises, and breathing speeds up and becomes more irregular. Small twitches in face and fingers may occur; in men, the penis becomes somewhat erect as vascular tissue relaxes and blood fills genital area faster than it exits; in women, clitoris enlarges and vaginal lubrication increases. At same time, most skeletal muscles go limp, preventing aroused brain from producing physical movement. Have entered realm of REM.  Brain extremely active while body is entirely inactive so REM sleep has been called “paradoxical sleep”, vivid dreams occur here o Dream reports occurred 82% of the time when sleepers were awakened during REM sleep but they also occurred 51% of the time when people were awakened during non- REM sleep o Non-REM dreams tend to be shorter, less vivid, and more realistic than REM dreams, except in the hour or so before a person wakes up in morning  Occasionally as sleeper wakes up, curious phenomenon occurs. Person emerges from REM sleep before muscle paralysis characteristic of stage has entirely disappeared and becomes awake of inability to move o 30% of pop has experienced and about 5% had “waking” dream in state o Eyes are open but “see” dreamlike hallucinations, mostly shadowy figures- may “see” ghost or alien sitting on bed or hovering in hallway, scary image they would regard as perfectly normal if part of midnight nightmare. Instead, some interpret experience literally and believe they’ve been visited by aliens or being haunted  REM and non-REM sleep alternate throughout night, cycles far from regular  Reasons for REM sleep controversial  In some rare cases, brain-damaged patients lost capacity to dream yet continue to show normal sleep stages including REM  All mammals experience REM sleep except for bottlenose dolphins and porpoises  “No one, but no one, has been able to come up with a convincing explanation for REM sleep” – G.William Domhoff Why We Sleep  Appears to provide time-out period so body can eliminate waste products from muscles, repair cells, conserve or replenish energy stores, strengthen immune system, or recover abilities lost during day  Bodies operate abnormally if don’t get enough sleep o Levels of hormones necessary for normal muscle development and proper immune system functioning decline  Sleep deprivation that lasts for four days or longer quite uncomfortable and soon becomes unbearable o In animals, forced sleeplessness leads to infections and eventually death- same true for people o 51 year old man abruptly began to lose sleep- developed lung infection and died after sinking deeper and deeper into exhausted stupor. Autopsy showed that he had lost almost all of the large neurons in two areas of the thalamus that have been linked to sleep and hormonal circadian rhythms The Mental Consequences of Sleeplessness  Sleep necessary for normal mental functioning  Chronic sleep deprivation increases levels of the stress hormone cortisol which may damage or impair brain cells that are necessary for learning and memory. New brain cells may either fail to develop or may mature abnormally also  After loss of even single night’s sleep, mental flexibility, attention, and creativity all suffer  After several days of staying awake, people may even begin to have hallucinations and delusions  3.3 million Canadians (1/7 of people over 15) are plagued by chronic insomnia (difficulty falling or staying asleep)  Insomnia can result from worry and anxiety, psychological problems, physical problems (arthritis), and irregular or overly demanding work and study schedules  Canadian study of insomnia (Laval University’s Charles Morin), followed 400 insomniacs undergoing treatment for condition- 54% improved with treatment but 27% relapsed afterward- treatment only short-term solution  Sleep apnea: a disorder in which breathing briefly stops during sleep, causing the person to choke and gasp and momentarily awaken o Most seen in older males and overweight people o Several causes from blockage of air passages to failure of brain to control respiration correctly o Can cause high blood pressure and irregular heartbeat; may gradually erode a person’s health and is associated with shortened life expectancy over time  Narcolepsy: a sleep disorder involving sudden and unpredictable daytime attacks or sleepiness or lapses into REM sleep o Lasts from 5-30 minutes o ~2700 Canadians suffer from condition without knowing o Seems to be caused by degeneration of certain neurons in hypothalamus, possibly owing to an autoimmune malfunction or genetic abnormalities  REM Behaviour Disorder: a disorder in which the muscle paralysis that normally occurs during REM sleep is absent or incomplete, and the sleeper is able to act out his or her dream o Usually male o If dreaming about football, may try to tackle piece of furniture; if dreaming about kitten, may try to pet o Unaware of what he is doing  Two-thirds of all North Americans get fewer than recommended seven or eight hours of sleep and students only get six on average  Some people do fine of relatively few hours of sleep but most adults need six for optimal performance and many adolescents need ten  When people don’t get enough sleep, more likely to get into traffic or work accidents  In US, National Transportation Safety Board estimates that drowsiness is involved in 100 000 vehicle accidents a year, causing 1500 road deaths and 71 000 injuries  Sleep deprivation also leads to accidents in workplace, concern especially for first-year doctors doing medical residency  Many countries limit work hours for airline pilots, truck drivers, and nuclear-plant operators, but medical residents still often work 24-30 hour shifts  Lack of sleep linked to lower grades  Sleep researcher James Maas noted that many high school and college students drag themselves through day “like walking zombies… moody, lethargic, and unprepared or unable to learn” The Mental Benefits of Sleep  Study- students who slept for eight hours after learning lists of nonsense syllables retained them better than students who went about their usual business  Scientists believe sleep plays more active role by contributing to consolidation: a process by which they synaptic changes associated with recently stored memories become durable and stable, causing memory to become more reliable  One theory is that during sleep the neural changes involved in recent memory are reactivated, making those changes in memory more permanent  Improvements in memory have been associated most closely with REM sleep and slow-wave sleep (stages 3 & 4) and with memory for specific motor and perceptual skills  Sleep also seems to strengthen other kinds of memories, including recollection of events, locations, and facts  Emotional memories, especially, are improved with sleep: when people look at emotionally arousing scenes in morning or evening and are then tested for their memory of materials after 12 hours of daytime wakefulness or nighttime sleep, those tested after sleeping recall the emotional scenes more reliably that neutral ones o Also do better on negative emotional scenes than other participants do  Sleep also enhances problem solving- relies on information stored in memory  We sleep to remember but we also sleep to forget so that brain will have space and energy for new learning  Even quick nap helps mental functioning and increases ability to put together separately learned facts in new ways  During sleep, periods of (REM) alternate with non-REM sleep in approximately a 90-minute rhythm. Non-REM sleep is divided into four stages on the basis of characteristic brain-wave patterns. During REM sleep, the brain is active, and there are other signs or arousal, yet most of the skeletal muscles are limp; vivid dreams are reported most often during REM sleep. Some people have had “waking dreams” when they emerge from REM sleep before the paralysis of that stage has subsided and, occasionally, people have interpreted the resulting hallucinations as real. The purposes of REM are still a matter of controversy  Sleep is necessary not only for bodily restoration but also for normal mental functioning. Many people get less than the optimal amount of sleep. Some suffer from insomnia, sleep apnea, narcolepsy, or REM behaviour disorder. Researchers are concerned about the growing number of sleep-deprived people in modern societies  Sleep may be necessary for the consolidation of memories. Improvements in memory due to sleep have been associated most closely with REM sleep and slow-wave sleep and with memory for specific skills. Sleep also seems to improve insight and problem solving Exploring the Dream World  Every culture has theories about dreams o In some, dreams are believed to occur when spirit leaves body to wander world or speak to gods, in others, dreams thought to reveal future  Everybody dreams unless suffered some brain injury  In dreaming, focus of attention is inward but external event such as wailing siren, can influence dream’s content occasionally  While dream is in progress, may be vivid or vague, terrifying or peaceful; may also seem to make perfect sense- until awake and recall it as illogical, bizarre, and disjointed  Some say they occasionally have lucid dreams: dreams in which the dreamer is aware of dreaming; few even claim to be able to control action in these dreams  Issue that has bothered sleep researchers for years is whether eye movements of REM sleep correspond to events and actions in a dream. o Are eyes tracking these images? o Some believe that in adult dreamers, eye movements resemble those of waking life, when eyes and head move in synchrony as person moves about and shifts gaze o Others think eye movements are no more related to dream content than are inner-ear muscle contractions which also occur during REM sleep Dreams as Unconscious Wishes  One of first psychological theorists to take dreams seriously was Sigmund Freud- founder of psychoanalysis  After analyzing many of patients’ dreams and some of his own, Freud concluded that our nighttime fantasies provide insight into desires, movies, and conflicts of which we are unaware- a “royal road to the unconscious”  In dreams, said Freud, we are able to express our unconscious wishes and desires, which are often sexual or violent in nature  According to Freud, every dream is meaningful no matter how absurd images may seem  But if dream’s message arouses anxiety, rational part of mind must disguise and distort it otherwise, dream would intrude into consciousness and waken dreamer o Therefore, one person may be represented by another (ex. Father by a brother), or even several different characters o Similarly, thoughts and objects are translated into symbolic images. Penis may be disguised as a snake, umbrella, or dagger; vagina as a tunnel or a cave; and human body as house  Because reality is distorted, dream resembles psychosis, a severe mental disturbance; each night, we must become temporarily delusional so that our anxiety will be kept at bay and sleep won't be disturbed  To understand a dream, said Freud, we must distinguish its manifest content, the aspects of it that we consciously experience dur
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