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Chapter 5

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Todd Ferretti

Chapter 5 Biological Rhythms Biological Rhythms  A periodic, more or less regular fluctuation in a biological system  Rhythms can be synchronized with external (entrainment) or internal cues (endogenous)  Biological rhythms influence effectiveness of medication, alertness, job performance Circadian Rhythms  Circadian Rhythms occur approximately every 24 hours (e.g. sleep-wake cycle) -Commonly entrained to external time cues -Endogenous rhythm averages around 24.3 hours -Removed from cues about 10% of people have clocks running slower and 10% running faster -Increase in accidents at transition to Daylight Savings Time -Controlled by biological clock in suprachiasmatic nucleus (SCN) -Regulates levels of melatonin secreted by pineal gland Out of Sync  Internal Desynchronization - A state in which biological rhythms are not in phase (synchronized) with one another -Changes in your normal routines can cause desynchronization -May also occur in responses to jet lag, rotating shift work, daylight savings time Mood and Long Term Rhythms  Seasonal Affective Disorder -A disorder in which a person experiences depression during the winter and improvement of mood in the spring -Treatments may involve phototherapy or exposure to fluorescent light -Inconsistent findings with respect to prevalence (2-20%) and effectiveness of treatments -NOT A FORM OF DESYNCHRONIZATION Mood and Menstrual Cycles  "Premenstrual Syndrome" (PMS) -Vague cluster of physical and emotional symptoms associated with the days preceeding mensturation that was labelled as an illness -Physical symptoms (e.g. cramps, water retention) are common -Emotional symptoms (e.g. irritability, depression) are rare Mood, PMS, and Research  Estimates of prevalence range from 13% to "most women"  Expectations and beliefs may be related to PMS symptom reporting  Evidence supports that women often experience physical symptoms, but emotional symptoms are relatively rare  Recent research suggests that it's a social construction The Rhythms of Sleep  During sleep, we cycle between periods of REM and non-REM sleep (approx. 90 minutes) -Rapid Eye Movement (REM): characterized by eye movement, loss of muscle tone, and dreaming -Non-REM(NREM) sleep: characterized by fewer eye movements than in REM -Divided into 4 stages with different brain waves -Relaxed brain associated with alpha waves (see page 155 or 165 in textbook for picture regarding sleep brain activities) The Stages of Sleep  Stage 1: -feel on the edge of consciousness; light sleep  Stage 2: -presence of sleep spindles; minor noises wont disturb you  Stage 3: -delta waves begin; breathing and pulse have slowed down; hard to awaken  Stage 4: -delta waves predominant; deep sleep; most likely stage for sleepwalking  REM Sleep: increased eye movement, loss of muscle tone and dreaming  Dream throughout the sleep cycle, just not as frequently as during REM  Last REM period of the night has the most eye movement, period where dreams are usually remembered from Why We Sleep  Exact function of sleep unclear  However allows for certain processes to occur: -Body eliminates waste products from muscles -Repairs cells -Conserves and replenishes energy stores -Strengthens immune system -Recovers abilities lost during the day -Necessary for normal mental functioning Sleeplessness  Chronic sleep deprivation -Increases cortisol levels which can impair neurons involved in learning and memory  Chronic Insomnia -Difficulty falling or staying asleep; about 3.3 million Canadian adults experience this  Daytime sleeplessness linked to inadequate sleep during night, associated with decreased mental performance Sleep Disorders  Sleep Apnea -Disorder in which breathing briefly stops during sleep, causing person to choke and gasp and momentarily awaken  Narcolepsy -Disorder involving sudden and unpredictable daytime attacks of sleepiness or lapses into REM sleep  REM behaviour disorder -Muscle paralysis associated with REM sleep does not occur, and sleeper (mostly males) may "act out" their dreams Benefits of Sleep  Memory Consolidation -Process by which the synaptic changes associated with recently stored memories become durable and stable, causing memory to become more reliable -Linked to REM and slow-wave sleep -May also enhance problem-solving abilities Exploring the Dream World  Most people dream, although may not be aware -Lucid Dreams: dream in which the dreamer is aware that they are dreaming, maybe be able to exert some control over dream  Various theories proposed to explain the purpose of dream: -Psychoanalytic, problem-focused, cognitive, activation-synthesis Dreams As Unconscious Wishes  Psychoanalytic approach to dreaming (Freud)  Dreams provide insight into unconscious wished and desires - "a royal road to the unconscious" -Manifest Content: aspects of dreams that are consciously experienced; may involve "day residue" -Latent Consent: aspects of dream that are unconscious wishes being expressed symbolically Dreams as Problem Solving  Problem-focused approach to dreams -Explanation in which the symbols and metaphors in a dream do not disguise its true meaning , they convey it -Dreams often contain material related to our current concerns (e.g. work, sex, etc) -May provide opportunities to resolve problems Dreams As Thinking  Cognitive approach to dreaming  Dreams reflect modifications of cognitive activity that goes on when we are awake -E.g. most likely to dream about topics that occupy waking thoughts  Cut off from sensory input and external feedback during dreaming Dreams As Brain Activity  Over course of the night spontaneous firing of neurons in Pons to different parts of the brain  Cerebral cortex synthesizes signals, tries to interpret them ("I'm running through the woods.")  Activation -synthesis theory of dreaming o Dreaming results from cortic
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