Unit 3 Psychology ~ 2013

Transcription

1 Unit 3 Psychology ~ 2013

2 Sleep is described as regularly occurring altered state of consciousness that typically occurs spontaneously and is characterised by a loss of conscious awareness Sleep occurs naturally Various drugs such as alcohol, and tranquillizers can induce sleep. Polysomnography: intensive study of a sleeping person 2

3 3 During the night we experience TWO types of sleep: REM = Rapid Eye Movement NREM = Non-Rapid Eye Movement Summary of the PHYSIOLOGICAL characteristics of REM & NREM:

4 Fifth stage of sleep Rapid Eye Movement The brain and internal organs are very active Neurons behave the same as when we are awake Low amplitude, high frequency beta waves, similar to those seen when awake. Heart rate, breathing rate & metabolic rate all become irregular Complete paralysis of the muscles of the body Due to this inconsistency (active mind & organs; passive muscles) this stage of sleep is also known as PARADOXICAL sleep REM periods lengthen and occur closer together as the night progresses Deep sleep, difficult to wake Most dreaming occurs during REM sleep The sleeper is relaxed except for occasional muscle twitching. 4

5 Non-Rapid Eye Movement Approximately 80% of sleep is NREM Eyes move very slowly (if at all) Neural activity in the brain slows down Heart rate, breathing rate & metabolic rate are more regular NREM includes stages 1-4 of the sleep cycle NREM lasts mins for adults Stages 1 to 4 are characterised by different depths of sleep. Psychologists know the type of sleep being experienced by looking at an EEG. Occurs in continuous cycles 5

6 We have an alternating pattern of being awake and falling asleep It is an example of a CIRCADIAN RHYTHM a 24 hour cycle The sleep segment of the cycle has alternating REM and NREM stages 6

7 Secreted by the pineal gland in the brain Hormone associated with the onset of sleep It is secreted in larger quantities when it is dark When it enters our bloodstream in the evening it causes sleepiness, hence encouraging sleep Levels of melatonin decrease in the morning Melatonin works together with the environment to regulate the sleepwake cycle 7

8 Sunlight prompts the body to wake up Exposure to light stimulates a nerve pathway from the retina to the hypothalamus (in the brain) The hypothalamus contains a special structure that acts like a clock, regulating patterns of activity in the body As exposed to light, this structure increases body temperature and releases cortisol It also sends a message to the pineal gland in the brain to decrease the release of melatonin 8

9 Stages 1 & 2 are light sleep Stages 3 & 4 are deep sleep REM sleep is the 5 th stage of sleep When we fall asleep we go through the stages in this order : REM This makes up ONE CYCLE that can last between minutes (average 90 minutes) 9

10 Awake REM Stage 1 Stage 2 Stage 2 Stage 3 Stage 3 Stage 4 10

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13 NREM Stage 1 NREM Stage 2 NREM Stage 3 NREM Stage 4 Lasts 5 10 minutes As we drift to sleep, still slightly aware of environment. Physiologically, heart rate, body temp and respiration decrease. Muscles relax and sometimes jerk which is called the hypnic jerk. Alpha waves are being replaced by theta waves. Lasts for minutes Light stage of sleep Body temperature etc. continue to decrease, Brain waves are mainly theta waves but are lower if frequency. Brief bursts of high frequency brain waves occur called sleep spindles, indicates a person is really asleep. Bursts of low frequency and high amplitude called K complexes occur in response to arousing stimuli. Lasts minutes Moderately deep sleep Reduction of brain electrical activity Delta waves Arrival of Delta waves marks the beginning of slow wave sleep which has slower frequency delta waves. Deep sleep. Delta waves dominate. Stages 3 and 4 decrease closer to waking which suggests that the sleep earlier in the night in better quality. During stages 3 & 4 sleep phenomena may occur: sleepwalking, sleep talking, night terrors. If person is woken during this stage they can be disorientated called sleep inertia 13

14 Lasts for about 5-10 minutes Brain waves irregular in frequency Theta waves: 3-7 Hz (mixture of high & low amplitude) Decrease in heart rate, respiration, body temperature and muscle tension Slow rolling movements of the eyes 14

15 Lasts for about 20 minutes Body movements lessen, breathing becomes more regular, blood pressure, temperature & heart rate continues to decrease. Theta waves, with SLEEP SPINDLES These are brief periods of Hz waves Some sharp rises and falls in the wave pattern, called K COMPLEXES in response to arousing stimuli. Considered to be light sleep as people will respond to strong or loud stimuli. 15

16 The start of the deepest period of sleep Heart rate, blood pressure & body temperature continue to drop Breathing rate is slow & steady Slow wave sleep (SWS) Very slow waves of a large amplitude Delta waves (1-2 Hz) make up 20% - 50% of brain wave recordings If woken during stage 3 person is usually disoriented 16

17 The deepest stage of sleep Stages 3 and 4 initially last 30 minutes and decrease as the night progresses Muscles are completely relaxed & there is very little movement. Delta Waves make up more than 50% of the brain wave patterns. Delta waves are slower & larger than those in stage 3. A person in stage 4 is difficult to wake. If woken during this stage, the person can take up to 10 minutes to orient themselves and have poor memory of sleep events (sometimes called sleep drunkenness ) 17

18 During stages 3 & 4 sleep phenomena may occur: sleepwalking, sleep talking, night terrors. Bedwetting may occur during stages 3 or 4. Stages 3 & 4 are longer earlier in the night By morning, stages 3 & 4 are generally not experienced at all 18

19 Beta waves similar to brain activity when awake The first cycle of REM sleep lasts approximately 10 minutes and increases as the night continues By morning almost all of our sleep is spent in Stages 2 and REM sleep Eyes are moving quickly in jerking movements Muscle atonia complete loss of muscle tone of the limbs & torso Occasional twitch in the face, fingers or toes DREAMS occur during REM sleep 19

20 Everyone dreams! Dreams can occur during all stages of sleep Dreams during REM sleep are more intense, vivid, colourful and memorable compared to the dreams in NREM Dreams in NREM tend to be shorter, less frequent and consist of simple experiences NREM dream recall is vague and disjointed Nightmares occur in REM sleep and are more common in children Nightmares can occur during times of stress, fatigue or after personal trauma The reason that a nightmare occurs is not well understood 20

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22 Protection from danger Conserve energy Restore & repair damage to neurons in the brain Restore and repair damage to cells and tissues in the body Remove waste products built up in the muscles Allow for growth and development Maintain proper function of the nervous system Maintain normal cognitive functioning Strengthen neural connections in the brain Process memories and information learnt during the day 22

23 Why do we need to sleep? Below are 3 theories that have been proposed: Restoration theory Sleep provides time out to help us recover from depleting activities NREM sleep restores and repairs the body, while REM sleep restores the brain and is involved in processes of memory and learning. Survival theory also called evolutionary theory Sleep evolved to enhance survival making us inactive during the most risky part of a day Sleep conserves energy and protects organisms from danger. Consolidation theory Processing of information that has been learnt and strengthen new memories 23

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25 Lines/patterns on a graph that are produced when electrical activity of the brain is detected and recorded The brainwave pattern identifies when a person is in a light or deep stage of sleep or the level of alertness when awake Brainwaves are measured with an ELECTROENCEPHALOGRAPH (EEG) FREQUENCY number of brainwaves per second (width of the wave) High frequency = lots of waves close together AMPLITUDE the intensity of the brainwaves (height of the wave) High amplitude = bigger peaks and troughs 25

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27 The waves are described according to the size and height (frequency & amplitude) BETA waves high freq; low amp; produced during REM sleep and when awake/alert ALPHA waves high freq; low amp; (lower freq & higher amp than beta waves); produced during stage 1 sleep and when very relaxed or meditation THETA waves medium freq; mixture of high & low amp; primarily during stage 3 DELTA waves low freq; highest amp; slow wave; deep sleep; produced during stage 4 sleep Sleep Spindles short burst of high frequency brain waves; signifies the onset of sleep K-complexes single burst of low frequency & high amplitude; occurs in response to environmental stimuli or muscle tension 27

28 Awake Stage 1 Stage 2 Stage 3 Stage 4 Beta Alpha & Theta Theta Theta & Delta Delta REM Beta 28

29 Awake/Alert NREM Stage 1 29

30 30 NREM Stage 2 NREM Stage 3

31 NREM Stage 4 REM Stage 5 31

32 Electrooculargraph (EOG): Measures eye movements by detecting, amplifying and recording electrical activity in eye muscles that control movements. Used to define differences between types of sleep such as REM. Heart rate: Can increase or decrease in altered states of consciousness vs. normal waking consciousness decreases during meditation increase after taking stimulants e.g. coffee, cocaine. Can suddenly and dramatically change during sleep e.g. during a nightmare Body temperature: Drops as we progress from light sleep into deeper sleep then increases as we go the reverse way 32

33 Label each area with the appropriate measurement equipment 33

34 There are 3 main ways to study the physiology of sleep. EEG Electroencephalogram EMG Electromyogram EOG Electro-oculogram Sleep researchers use these devices to record the changes that occur in our brains during sleep. 34

35 A graph showing the pattern of brain waves or the brain s electrical activity. External electrodes are attached to the surface of the scalp. The electrodes measure the combined electrical output of neurons firing in the cortex below the scalp. 35

36 A device that measures the electrical activity in the muscles. This indicates the changes in muscle activity (movement) and muscle tone (tension). Electrodes are attached to the skin above the muscles being measured, including: Facial muscles Leg muscles Trunk muscles Or a combination of these The muscles under the chin are often used because the activity of the jaw muscles in this area show dramatic changes during sleep. 36

37 A measure of the electrical changes associated with the spontaneous eye movement activity during sleep. The electrode is placed on the skin near each of the eyes. The eyeball rotates and changes voltage with this rotation. This method has been very useful in identifying two distinctly different types of sleep called rapid eye movement and nonrapid eye movement. 37

38 EEG What does it measure? Brain wave activity Location of electrodes Scalp EMG Muscle tension Muscles: face, legs, trunk EOG Eye movement Near each eye 38

39 Galvanic skin response (GSR): Physiological response that indicates change in skins resistance to electrical current. To measure, electrodes attached to hairless part of the body. Sweat makes the body less resistant to electrical current, emotional responses can trigger sweat and therefore can be measured. Other physiological responses: Respiration Amount of oxygen in the blood Body position Leg movements Snoring noises 39

40 Sleep laboratories Often attached to hospitals bedrooms attached to control rooms where researcher s monitor Recordings of EEG, EOG and EMG s are taken Video monitoring Use infrared light so person is not woken Measures involuntary sleep behaviours (e.g. sleepwalking) Self reports Questionnaires Sleep diaries Waking participants and asking them to describe Useful to know thoughts and feelings 40

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42 Refers to going without sleep. Generally results in a range of symptoms including irritability, tiredness, lack of concentration & motivation, headaches and lack of energy. There are 3 broad categories of sleep deprivation: total deprivation, partial deprivation selective deprivation Much of what psychologists have learned about the effects of total sleep deprivation has come from research with animals. It would be unethical, hence not permissible to conduct research in which humans were totally sleep deprived because of the potential for psychological and physiological harm. 42

43 Partial sleep deprivation refers to missing or lacking in sleep over a short period of time Over a short period of time minor effects Quick recovery once sleep debt is repaid No long term effect The effects of partial sleep deprivation: PHYSIOLOGICAL Tiredness Lack of energy Lapses in attention Impaired motor skills Headaches Impaired cognitive performance PSYCHOLOGICAL Inability to concentrate Low motivation Irritability Difficulty making decisions Difficulty being creative 43

44 Total sleep deprivation refers to having no sleep over a number of days The effects of sleep deprivation are temporary and only persist until the individual is able to sleep. Most people make up for lost sleep by getting a few extra hours of sleep over the next few nights. Sleep researchers argue that pure total and prolonged sleep deprivation is unachievable due to a person s tendency to experience micro-sleeps. Prolonged sleep deprivation results in a mild deficit of NREM sleep and s substantial deficit of REM sleep 44

45 Research has shown that when rats are totally deprived of sleep they die (Rechtschaffen 1997) Based on this research, Rechtschaffen proposed that sleep is vital to the regulation and stability of an animal s internal environment and that this may also apply to human. Sleep deprivation in humans is studied by either keeping the participants awake for extended periods of time or by reducing the duration of their sleep. See the case studies of Peter Tripp & of Randy Gardner. Total sleep deprivation is difficult to ensure because after 3-4 sleepless days people automatically drift into periods of microsleep over which they have no control. 45

46 Peter Tripp e=results_video&playnext=1&list=pl9426d8482dca196e Effects of sleep deprivation Fatal Familial Insomnia (30 minutes) lated Microsleep 46

47 Sleep deprivation can have negative effects, but not necessarily severe effects. Most people can only stay awake for 3-4 days. As a result, sleep researchers tend to focus on partial sleep deprivation as this occurs more often in our lives (as a result of work, school, family, social commitments). Examples of Psychological Effects: Performance on cognitive tasks is reduced Reduction in concentration, motivation & attention. These negative effects can be reversed if the participants are motivated by the researcher to perform better. Hallucinations and perceptual distortions 47

48 Most common effects include sleepiness and fatigue. Other effects include: Hand tremors Drooping eye lids Difficulty focusing eyes Lack of energy and strength Slurred speech Increased sensitivity to pain Slower heart rate Decreased respiration Drop in body temperature Impaired functioning of immune system Impaired production of hormones 48

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50 REM More dramatic effects than loss of NREM sleep High levels of anxiety, feelings of insecurity, poor learning, poor memory consolidation, inability to regulate body temperature NREM Growth hormone is released during NREM sleep, so deprivation results in slowed growth Hinders restoration of the body and efficiency to replenish energy stores 50

51 Sleep onset is shorter than usual (takes less time to fall asleep) The total time asleep on the first night after sleep deprivation increases Sleep time on the second & third nights is only slightly greater than normal It is not necessary to make up the entire amount of sleep that has been lost to recover from sleep deprivation Following a few good night s sleep there are no adverse long-term side effects of sleep deprivation EEG patterns show: On the first night of sleep there is an increase in slow-wave sleep On following nights, there is a significant increase in REM sleep 51

52 Catching up on REM sleep Occurs immediately following a period of prolonged sleep deprivation The sleeper spends more time than usual in REM sleep when next asleep 52

53 The body s way of fighting total sleep deprivation A very short period of drowsiness or sleeping that occurs when the person is apparently awake There is no memory of what occurred during the microsleep During a microsleep, the EEG pattern resembles that of NREM sleep. Lasts about 30 seconds 53

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55 Time spent sleeping decrease as we get older as does time spent in REM sleep Biological influences: Biological clock which works like an inbuilt timing system Circadian rhythm cycle of hormones that are produced to control body functions such as the release of melatonin which cause sleepiness. Is linked to external cues such as daylight, meal times, and alarms. Sleep-wake cycle shift- hormones that induced a shift of the body clock forward by 1-2 hrs resulting in sleep phase onset Sleep phase onset Biologically driven need to sleep one or two hours longer Sleep debt Missed sleep is owed and needs to be made up 55

56 Stage of Lifespan Sleep needed per day (hrs) Infants hrs 1 year olds hrs 3-5 year olds hrs Children 8-10 hrs Adolescents 9-10 hrs Adults 7-8 hrs Elderly 6-7 hrs, possibly 8 56

57 16 17 hours of sleep a day Newborns spend most of their time sleeping They sleep and wake about 4-5 times per day By 6 months of age, the infant needs hours sleep By 1 year of age, the baby needs hours sleep REM sleep takes up about 50% of the sleep time Neural connections are strengthened during REM sleep hence the baby is undergoing rapid cognitive development Visual and auditory functions are also being developed 57

58 10 12 hours sleep per day for 3 5 year olds High levels of stages 3 4 sleep 20% of sleep is REM sleep 8 10 hours sleep per day for 10 year olds Further cognitive development occurs (REM) Physical development of the body also occurs (NREM) A regular bed time schedule is recommended Nightmares, night terrors, sleepwalking and bedwetting are common experiences for children 58

59 9 10 hours of sleep per day is recommended However it s likely that most teenagers sleep less than what is recommended Researchers believe that teenagers are suffering from sleep deprivation but do not realise it Teenagers experience significant changes in their sleep patterns 59

60 Total time sleeping is shorter than childhood Delayed onset of sleep (go to bed later) Tend to sleep-in longer in the morning Increased daytime sleepiness Less sleep on weekdays due to going to bed late and having to get up early for school Sleep more on weekends to make up for lost sleep during the week 60

61 Teenagers have a greater tolerance for sleep deprivation Decreased slow-wave sleep (40% less) which is replaced by stages 1 & 2 sleep This increase in lighter sleep may account for daytime sleepiness Night terrors, teeth grinding, sleep walking, sleep talking and extreme sleepiness is common in teenagers 61

62 Experienced during adolescence Refers to the change in the timing of a person s circadian rhythm Results in a mismatch between internal biological cues and the external environmental cues to go to sleep at night and to wake up in the morning Attributed to both social and biological factors 62

63 SOCIAL FACTORS Greater homework demands After-school sporting activities Part time employment Watching late-night TV Internet usage Decreased parental monitoring and control BIOLOGICAL FACTORS Physical development associated with puberty Hormonal changes Melatonin is secreted later in the evening in adolescents 63

64 Refers to a shift of the body s timing system causing extreme sleepiness upon waking in the morning Sufferers have difficulty falling asleep at night and waking up at the expected times Can be treated with exposure to bright light in the morning or taking melatonin as medication Often associated with depression 64

65 8 hours of sleep per day REM sleep takes up 20% of sleep The sleep-wake cycle tends to shift back to an earlier time Many adults will not be getting enough sleep due to social factors (trying to fit in too many things in the day) 65

66 6 7 hours sleep per day Less sleep required due to sedentary lifestyle Recent research shows that elderly actually require SAME amount of sleep as adults but are unable to achieve this level Less slow-wave sleep, sometimes having NO stage 4-4 sleep Results in decreased brain plasticity REM sleep only decreases slightly 66

67 Delayed onset of sleep due to medical conditions Increased awakening during the night to go to the toilet Other medical reasons disrupting sleep: Parkinson s disease Arthritis pain Heart disease Reflux Respiratory conditions The brain secretes less melatonin, resulting in delayed sleep onset Increased sleep disorders common in the elderly 67

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69 Sleep Profile Sleep problems & advice Why do we sleep? Daily rhythm TV program Sheep Dash (test your reaction time) Face memory Test Sleep Quiz Info to help deal with insomnia Wide range of information about sleep 69