Sleep States

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  • Created by: Amy
  • Created on: 15-01-13 15:29
What is an encephalograph and why is it used?
A recording of the electrical acitivity in the brain. It can reflect arousal and stages of sleep
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What are EOGs and EMGs, respectively?
Recording of eye movements; recording of muscle movements
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What is a desynchronised EEG?
A reading that has no regular pattern of electrical activity. Typically recorded when the brain is active
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What is a synchronised EEG?
A reading that has a regular pattern of electrical activity
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What happens in NREM?
Respiration, heart rate, blood pressure, blood flow to the brain falls (becoming less active); occurs in 4 stages
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What did Dement and Kleitman discover about how long REM lasts with EEG measurement in the sleep lab?
REM lasts about 15 minutes in the 1st cycle and builds up to an hour by the 4th and 5th cycle
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What else did they find?
EEG showed beta waves - which occur during a relaxed waking state; EMG shows the body is paralysed; dreaming occurs; hardest stage to be awakened from
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What are strengths of the sleep lab method?
EEG, EOG, EMGs provide objective measures of sleep; reliable scientific method; ethical
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What are weaknesses of the sleep lab method?
It cannot show exactly which areas are involved in each stage of sleep; sleep lab is an artificial condition as wired up; reductionist; patterns of sleep vary from each individual
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What do evolutionary psychologists believe sleep does?
It has evolved into an essential behaviour because it provides selective advantages
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What do they believe sleep is for?
Not a basic physical function (not strictly necessary); but has other functions such as energy conservation and safety
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What is an ecological niche?
An animal's lifestyle - how and where they live
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How do aquatic animals sleep differently to land animals?
Dolphins sleep with one side of the brain at a time
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All animals are either nocturnal or?
Diurnal
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What does this mean?
They have adapted to be active only in part of every 24 hours
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What types of animals are more vulnerable in sleep?
Prey
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What are examples of sleep sites?
Exposed location like the African Savannah or a safe, deep burrow
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How does size affect sleep?
Large animals sleep less than smaller animals
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Why is this?
Either lifestyle or different physiology
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What is Meddis' explanation of sleep?
Predator-prey status
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Explain this?
Sleep keeps vulnerable animals safe, diurnal animals cannot forage food at night so sleep evolved to keep prey safe; animals at risk from predators would have evolved to sleep more to stay safe; sleep is affected by risk of danger and food gathering
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What is Webb's hibernation theory?
Hibernation and sleep are to conserve energy when foraging would be difficult or impossible; animals are inactive whilst asleep - conserves energy; animals with high metabolic rate sleep more(use more energy);
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What did Allison and Cicchetti find in 39 animal species?
Prey animals sleep for significantly less time than predators
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Whose theory does this oppose?
Meddis' predator-prety status - sleep keeps vulnerable prey animals safe
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What did Lesku find about prey animals?
They are often herbivores and therefore need to spend most of their time grazing which may explain why they sleep less
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What does this hibernation theory show in the basal metabolic rate(BMR)?
It is positively correlated with sleep time (the higher the BMR, the more the animal sleeps - to conserve energy_
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Who found this?
berger and Phillips
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What does this suggest?
Small animals have a higher BMR than large animals, therefore they sleep more
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Whose theory does this contradict?
Meddis - predator-prey status.
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However, why might this be?
Because their sleep site has a bigger effect on the evolution of sleep (still evolutionary - safe from prey) Prey animals = herbivores, they need to graze a lot suggesting evolution is still affecting sleep
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Whose theory does this support?
Webb, sleep has evolved to conserve energy
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What did Lesku et al study?
Analysed sleep patterned for 54 species and studied body/brain mass, BMR, sleep exposure and whether the animal was a herbivore or a carnivore
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What did they find?
Brain mass positively correlated with REM, sleep site negatively correlated with REM (more in danger, less REM - easily awakened); herbivores have less REM than carnivores (carns less likely to be attacked)
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What did they conclude?
Sleep time and proportions of REM and NREM are influenced by a range of factors; different animals sleep for different amounts of time because they have adapted to survive in their ecological niche
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Why does this support for evolutionary theory?
Shows animals adapt to their environment and vulnerability
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What strengths are there for this study?
High external validity as based on observations of animals in natural habitats; good indication of effects of evolution on sleep cycles
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What are the weaknesses of this study?
Correlation evidence is a weakness because we are unable to establish cause and effect; may bot show the effect of evolution on sleep cycles
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What is an argument against the view that sleep has an important adaptive function?
Sleep is found in species that would seem to be better off without it
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What are Indus Dolphins (Pilleri)?
They live in muddy waters of the Indus River in Pakistan and have evolved blindness because good eyesight is unnecessary in the poor visibility of their environment
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What did Pilleri find?
They have an excellent sonar system which lets them find prey while dodging the debris carried by the river in the monsoon. Despite these dangers of injury from floating debris, sleep has not disappeared.
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How often does the dolphin sleep?
Short naps between 4-60 seconds for a total of about 7 hours a day
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Why is this a complicated adaptation a problem for the evolutionary approach?
If sleep were only adaptive then it would have been eliminated through natural selection
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What are strengths of this theory?
high internal validity; can assess sleep patterns empirically; objective measuring;
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What is a weakness of this study?
Dolphins may not show normal sleep patterns in capitivity
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Who's case study of Fatal Familial Insomnia shows us that we need sleep in order to live?
Michael Corke
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What are the strengths of the evolutionary approach?
It takes the animal and its lifestyle into account, it considers a range of complicated factors to explain sleep behaviour - NOT REDUCTIONIST;
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What are weaknesses of the evolutionary approach?
Mostly animals - hard to generalise to humans; focus on nature; determinist
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What is Oswald's Restoration Theory?
Sleep is essential for survival, it has an essential function in restoring the body and mind
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What did Oswald find?
Noticed that more people recovering from trauma to the brain(drug overdoses) spent more time in REM; new skin cells grow during sleep; linked to increased release of body's growth hormone;
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What does he believe REM is important for?
Restoration of the brain
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What does he believe NREM is important for?
Restoration of the body
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Who spends a third of their time in REM?
Newborn Babies
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Why is this?
It is a time of massive growth with the development of new synaptic connections between neurons
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What is brain energy consumption during REM similar to?
Waking behaviour
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What are the main predictions of the Restoration Theory?
Deficits in functioning when sleep deprived; 'rebound effects' following sleep deprivation; increase in REm sleep during brain growth and repair; increase in NREM during times of illness/injury
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What would we expect if NREM has a physical restorative function?
An increase in it after excess physical excercise
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What did Shapiro find in people who had completed an 'ultra marathon' running 57 miles?
They slept for an extra 1.5 hours for the 2 nights after the race and stage 4 NREM took up a greater proportion of their total sleep time than usual
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What is the percentage of stage 4 NREM usually?
25%
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What was the percentage the athletes spent in NREM?
45%
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What does this study suggest about the effects of physical exercise on the body?
Supports the idea that NREM sleep is necessary to restore the body
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What did Ryback and Lewis find to the contrary?
They got healthy volunteers to spend 6 weeks resting in bed and found no change in their sleep patterns
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What does this suggest about the effects of physical exercise on sleep?
Restoration theory would predict less need for sleep, especially in stage 4 NREM, if participants were not physically active - but this was not the case
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Who was Peter Tripp and what did he do?
A radio personality who stayed awake for 8 days for a world record/charity
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What was he like before he did his study?
Nice, cheerful, upbeat,happy
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Why were sleep deprivation studies not popular with psychologists in the 1950s?
Soldiers got tortured through sleep deprivation and they saw the effects of it; they were changed men
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What were the effects of short term sleep deprivation?
Drop in body temp, hallucinations, delusions, 90 minute REM cycle; brainwaves showed he was asleep
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What were the long term effects?
He got divorced, couldn't recover sense of gravity, lost his job, no longer himself
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What are the strengths of this study?
High internal validity = never left alone, always had someone with him; had no time to recover/restore body/brain so his body forced him into sleeping; suggests we need REM
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What are the weaknesses of this study?
Only one person: population validity is low, hard to generalise
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What did Randy Gardner do?
Stayed awake for 11 days and achieved world record for total sleep deprivation
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Who observed him?
Dement and a colleague from 80-264 hours of sleep deprivation
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What happened at 80 hours of sleep deprivation?
Cheerful, happy, physically fit
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What happened after 10 days?
He was able to beat Dement on every game of baseball at an amusement arcade and spoke fluently
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When was it hard for the researchers to keep him awake?
Between 3am and 7am
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What were the short term effects of sleep deprivation?
Hallucinations; delusions; disjointed thinking; short attention span
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How long did Randy sleep for after?
24% of his missed sleep - 14 hours and 40 minutes - but caught up on most of missed REM and stage 4
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Why does this study support the Resoration theory?
Because he 'caught up' on his missed REM/stage 3; had hallucinations; no long term effects - we need sleep
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What's a weakness of this study?
Wasn't monitored until 80 hours without sleep; may not be valid
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What does Horne's restoration theory suggest?
We only need 'core' sleep: stage 3/4 REM and the disruption of this could cause problems. Stage 1&2 sleep is 'optional' and disruption has no impact
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What did he find?
Sleep deprived participants could not complete cognitive taks effectively indicating that sleep deprivation affects congnitive proccesses
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What are the strengths of Oswald's Restoration theory?
Psychology as a science - monitor sleep patterns scientifically; unbias and more valid
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What are the weaknesses?
Reductionist - the only need for sleep is to restore functioning. simplifies a complex behaviour and cannot explain all variations in sleep patterns between humans and animals (whereas evolutionary not reductionist)
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How much REM do we have as newborn babies?
A third of our time is spent in REM
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In old age what happens to our sleep pattern?
Night time sleep becomes fragmented and shorter; due to a reduction in melatonin released but this leads to sleepiness during the day and tendency to nap.
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Who are more likely to report sleep disorders?
Older people
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Large amounts of REM in newborns decreases when?
Over the first two years
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Between the ages of 5 and 70 what happens to NREM?
16% increase in stages 1&2 NREM and 60% decrease in deep NREM
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There is a steady reduction of what from age 30?
NREM
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What does this imply?
The needs for these functions declines with age
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What sleep changes are shown in older people with Alzheimer's disease?
A dramatic loss in deep NREM
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What does Alzheimer's patients having problems with learning and memory suggest?
There's a link between deep NREM and normal cognitive processes
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What are the strengths of lifespan changes
Scientific; not biased
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Weaknesses?
Cannot tell us WHY, little application purpose; reductionist
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Card 2

Front

What are EOGs and EMGs, respectively?

Back

Recording of eye movements; recording of muscle movements

Card 3

Front

What is a desynchronised EEG?

Back

Preview of the front of card 3

Card 4

Front

What is a synchronised EEG?

Back

Preview of the front of card 4

Card 5

Front

What happens in NREM?

Back

Preview of the front of card 5
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