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Chapter 5

Chapter 5. Body Rhythms & Mental States

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PSYC 1020H
Wolfgang Lehmann

Body Rhythms and Mental States  For 1/3 of our lives, we live in the dream world of sleep  During the day, mood, alertness, efficiency, and consciousness, are in perpetual flux  Consciousness: awareness of oneself and the environment Biological Rhythms: The Tides of Experience  Biological rhythms: a periodic, fairly regular fluctuation in a biological system, that may or may not have psychological implications  The biological clock in our brains governs the waxing and waning of hormone levels, urine volume, blood pressure, and the responsiveness of brain cells as stimulation  Entrainment is the synchronization of biological rhythms with external cues, such as fluctuations in daylight; these rhythms still occur even without external time cues as they are generated from within  Some rhythms can occur more frequently than others, such as seasonally, daily, monthly, or yearly Circadian Rhythms  Circadian rhythms: a biological rhythm with a period, which occur about every 24 hours  The sleep-wake cycle is the best known example of a circadian rhythm, but there are countless others affecting physiology and performance  Reflect the adaptation of organisms to many changes associated with the rotation of Earth on its axis, such as changes in light, air pressure, and temperature  To identify such endogenous rhythms, scientists now are isolated in specially designed rooms that are isolated from external time cues  For many people, alertness peaks in the late afternoon and falls to a low point in the very early morning (Lavie, 2001)  Circadian rhythms are controlled by a biological clock located in a cluster of cells within the hypothalamus called the suprachiasmatic nucleus (SCN)  Neural pathways from special receptors in the back of the eye transmit information to the SCN and allow it to respond to changes in light and dark, the SCN then sends out messages causing the brain and body to adapt to changes  SCN regulates the fluctuating levels of hormones and neurotransmitters, which then give feedback affecting the SCN’s functioning o Ex. Melatonin, a hormone regulated by the SCN, is secreted by the pineal gland located within the brain. When you sleep in a dark room, melatonin levels increase, and when you wake up in a lightened room it falls. Melatonin, in turn, appears to help keep the biological clock in phase with the light-dark cycle.  Melatonin therapy has been used to treat insomnia and synchronize the disturbed sleep-wake cycles of blind people lacking perception and those whose melatonin production doesn’t cycle normally  When normal routines change, your circadian systems can be thrown out of phase with another, known as internal desynchronization: a state in which biological rhythms are not in phase (synchronized) with one another Moods & Long-Term Rhythms  Modern science states that long-term cycles have been observed in everything from the threshold for tooth pain to conception rates  Seasonal affective disorder (SAD) states that people become depressed during particular seasons, generally winter, when periods of daylight are short  Patients of SAD report feeling sad, lethargic, and crave carbohydrates, and have sometimes been treated with phototherapy, antidepressants, and other drugs  Many clinicians believe SAD affects 20% of the population, while others think it is lower o Canadian estimates from Ontario mostly, suggest it is 2-3% of our population, compared to less than 1% of the USA  Most laypeople, doctors, and psychiatrists have uncritically assumed that many women ‘suffer’ from premenstrual syndrome (PMS) or from its supposedly more severe and debilitating version: premenstrual dysphoric disorder (PMDD)  Evidence shows that many women do experience physical symptoms (cramps, breast tenderness, water retention) associated with menstruation but emotional symptoms (irritability and depression) associated with menstruation are pretty rare The Realms of Sleep  Nathaniel Kleitman: was the first to spend his entire career studying sleep and gave a graduate student the task of finding out whether the slow, rolling eye movements characterizing the onset of sleep continue on throughout the night  They found that eye movements did occur but they were actually rapid, and were able to correlate the rapid eye movements with changes in sleeper’s brain-wave patterns  We know this today as rapid-eye movement (REM): sleep periods characterized by eye movement, loss of muscle tone, and dreaming which can last anywhere from a few minutes to an hour (averages about 20 minutes)  Non-REM periods are divided into 4 stages, each associated with a particular brain-wave pattern 1. Stage 1  Brain waves are small and irregular  Feel yourself on the edge of consciousness, in light sleep  If awakened, you may recall fantasies or a few visual images 2. Stage 2  Brain emits occasional short bursts of rapid, high peaking waves: sleep spindles  Minor noises likely not disruptive 3. Stage 3  Stage 2 brain waves continue, along with delta waves (very slow waves with very high peaks) occasionally being emitted  Breathing and pulse slow down, muscles relaxed, hard to awaken 4. Stage 4  Delta waves take over and you are in deep sleep now  Will probably take vigorous shaking or a loud noise to awaken you  More likely to walk in your sleep in this stage  This stage sequence takes about 30-45 minutes, and then move back up the ladder from stage 4-3-2-1  After about 70-90 minutes of sleep, stage 1 doesn’t turn into the expected drowsy wakefulness, instead the following happens:  Your brain emits long bursts of rapid, somewhat irregular waves  Heart rate increases, blood pressure rises, breathing speeds up and becomes more irregular  Small twitches in face and fingers may occur  In men, penis becomes somewhat erect and in women, the clitoris enlarges and vaginal lubrication increases  Most skeletal muscles go limp, preventing aroused brain from producing physical movement  All of those indicate that you have entered REM sleep  Dreams are most likely to occur during REM sleep, but can also happen after people are awakened from non-REM sleep too (dream reports occurred 82% of the time when sleepers were awakened from REM sleep and 51% of the time when awakened from non-REM sleep)  If you wake people up during REM sleep, nothing dramatic happens, but when they are able to return to sleep they will spend longer than normal in REM sleep and will become much harder to rouse  Although all mammals experience REM sleep (except for dolphins and porpoises) it is unlikely that rats and anteaters have the cognitive ability to construct dreams Why We Sleep  Generally, sleep provides a time-out period to eliminate waste products from muscles, repair cells, conserve or replenish energy stores, strengthen immune system, or recover abilities lost during the day  People can typically get along reasonably well with a day or two of sleeplessness, but sleep deprivation lasting 4 or more days becomes uncomfortable and eventually unbearable 1. The Mental Consequences of Sleep  Sleep is necessary for normal mental functioning  Chronic sleep deprivation increases level of stress hormone cortisol, that damages or impairs brain cells necessary for learning and memory  New brain cells may either fail to develop or mature abnormally  After several days of being awake, people may begin to develop hallucinations and delusions  About 3.3 million Canadians are plagued by chronic insomnia (about 1 out of 7 over age 15)  Another cause of daytime sleepiness is sleep apnea: a disorder in which breathing briefly stops during sleep, causing the person to choke and gasp and momentarily awaken  Narcolepsy: a sleep disorder involving sudden and unpredictable daytime attacks of sleepiness or lapses into REM sleep, these attacks may last from between 5 and 30 minutes  REM behaviour disorder: a disorder where the muscle paralysis that normally occurs during REM sleep is absent or incomplete, and the sleeper is then able to act out his or her dreams  The most common cause of daytime sleepiness is staying up late and therefore not getting enough sleep; 2/3 of all North Americans get fewer than the recommended seven or eight hours of sleep and students only get about six hours of sleep on average 2. The Mental Benefits of Sleep  Sleep plays a more active role by contributing to consolidation: a process by which the synaptic changes associated with recently stored memories become durable and stable, causing memory to be more reliable  Memory improvements have been associated closely with REM sleep and slow- wave sleep, as well as with specific motor and perceptual skills  Sleep strengthens the recollection of events, locations, and facts Exploring the Dream World  Lucid dreams: a dream in which the dreamer is aware of dreaming  Dreams are sometimes recalled as being illogical and disjointed  Various researchers disagree about whether eye movements of REM sleep are related to events and actions in dreams  4 different theories have been developed: dreams as unconscious wishes, dreams as efforts to deal with problems, dreams as thinking, and dreams as interpreted brain activity Dreams as Unconscious Wishes  Sigmund Freud was one of the psychological theorists to take dreams seriously  He concluded that nighttime fantasies provide insight into desires, motives, and conflicts of which we are unaware: a ‘royal road to the unconscious’  Freud said we are able to express our unconscious wishes and desire, often sexual or violent in nature, in our dreams  Says every dream is meaningful no matter how absurd the images, and that thoughts and objects are often translated into symbolic images  To understand dreams, we must distinguish its manifest concept (the aspect of it we consciously experience during sleep and will remember while awake), from its latent content (the unconscious wishes and thought being expressed symbolically) Dreams as Efforts to Deal with Problems  Dreams reflect the ongoing conscious preoccupations of waking life, such as relationship concerns, work, sex, or health  In this problem-focused approach to dreams, the symbols and metaphors in a dream do not disguise its true meaning – they convey it  Is supported by findings showing that dreams are more likely to contain material related to a person’s current concerns than chance would predict  Traumatic experiences can affect dreams also  Some psychologists believe dreams give us a chance to also resolve them Dreams as Thinking  The cognitive approach to dreaming emphasizes current concerns but makes no claims about problem solving during sleep  Views dreaming as a modification of the cognitive activity that goes on while we are awake, and we just construct reasonable simulations of the real world, drawing upon the same kind of memories, knowledge, metaphors, and assumptions about the world  The brain does the same kind of work during dreams as while awake, which is why parts of the cerebral cortex are highly activated during dreaming, but when we are asleep we are cut off from sensory input and feedback from the world and bodily movements Dreams as Interpreted Brain Activity  The activation-synthesis theory: a theory that dreaming results from the cortical synthesis and interpretation of neural signals triggered by activity in the lower part of the brain  This idea was first proposed by J. Allan Hobson, and said that dreams are not ‘children of an idle brain’  They are the result of neurons firing spontaneously in the lower part of the brain, in the pons, during REM sleep; these control eye movement, gaze, balance, posture, and send messages to sensory and motor areas of the cortex  The signals originating in the pons have no psychological meaning, but the cortex tries to make sense of them by synthesizing (integrating) them with existing knowledge and memories to produce a coherent interpretation  For instance, when neurons fire in the part of the brain affecting balance, the cortex may generate a dream about falling  Hobson and his colleagues added on saying that the brains tem sets off responses in emotional and visual parts of the brain  Hobson argues that wishes do not cause dreams, and that dream content may be: “as much dross as gold, as much cognitive trash as treasure, and as much informational noise as a signal of something”, but does not mean dreams are always meaningless Evaluating Dream Theories  Most psychologists accept Freud’s notion of dreams being more than incoherent ramblings of the mind and that they have psychological meaning, but consider the traditional psychoanalytic interpretation of dreams to be far-fetched as no reliable rules exist for interpreting the supposedly latent content of dreams; as well as there is no w
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