What is an electroencephalograph (EEG) and why is it used?
Electrodes placed on scalp record electrical activity of rain, different sleep states identified. Desynch EEG= no regular pattern (brain when awake). Synch EEG= regular pattern (brain when asleep).
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What type of rhythm is the sleep-wake cycle, and what type of rhythm is the cycle WITHIN our sleep?
Circadian Rhythm (takes place over 24 hours) and within sleep is an Ultradian Rhythm (cycle less than 24 hours- 90 minutes).
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What happens as we go through non REM sleep?
As we move through the sleep stages from drowsiness to stage 4 our respiration, heart rate and blood pressure fall. Blood flow to the brain falls showing it's less active.
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What are the characteristics of stage 1
Lightest stage of sleep: easily awakened. Hypnogogic hallucinations experienced. EEG charactised by theta waves (4-7 Hz).
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What are the characteristics of stage 2
Dominated by theta waves, bursts of of sleep spindles (12-16 Hz) that last for 1 or 2 seconds. Complexes also occur which are our responses to external stimuli.
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What are the characteristics of stage 3
Delta waves first appear (1-4 Hz)= larger amps than theta waves.
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What are the characteristics of stage 4
Large slow delta waves, deepest stage of NREM when people are most difficult to wake. Sleep-walking, sleep-talking and 'night terrors' can occur.
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What are the characteristics of REM
stage of dreaming, eyes dart around under eyelids, muscle paralysis, eeg is fast and de-synch'd: similar to pattern of an awake person. Paradoxical sleep.
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What is the general sleep cycle in terms of stages.
Describe the 1st-3rd cycle during an Ultradian Rhythm of sleep during the night.
1st: go down the sleep escalator from stage 1-4, then ascend through stage 3, 2. REM sleep follows this and lasts 10 minutes. 2nd: stage 2 for 20 mins, down to stage 3, 4 lasts 30 mins, REM for 10 mins. 3rd: stage 2, to 3, back to 2, then REM 40 mins
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Describe the 4th-5th cycle during an Ultradian Rhythm of sleep during the night.
4th: start at 2 then REM for 1 hours. 5th: start at 2, then REM sleep- known as emergent cycle as we may wake from either stage: more likely to remember dream if wake during REM.
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Evaluate the method of investigating stages of sleep.
+scientific evidence=not debatable, less likely to be effected by bias. Internal validity. -low eternal validity, individual diff's= mental health, insomnia.
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What are the issues and debates of stages of sleep?
Is psychology a science? Ethical: non-invasive, painless. Determinism. Nature v Nature.
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How much do babies sleep and what percentage do they sleep in REM/NREM?
Babies sleep for 16-20 hours per day. 50% in REM, 50% NREM. Premature babies may sleep in REM 80% of the time.
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How much do children of 1 year sleep? How much REM?
6-8 hours a night with 1-2 hours of daytime naps. Proportion of REM approaches 25%.
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Why do elderly people's night time sleep become shorter? What does this lead to?
A reduction in melatonin released. Leads to more naps, and therefore difficulty staying asleep/going to sleep. Older people also report more sleep disorders.
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What meta-analysis study supports the sleep stages?
Ohayon et al.
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What did Ohayon et al do?
reviewed 65 studies of sleeping patterns with an age range of 5-102 years old.
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What did Ohayon et al find?
5 year olds sleep for 470 mins, 5.8% stage 1, 47% stage 2, 25% stages 3+4, 25% REM. 70 year olds sleep for 370 mins, 6.8% stage 1, 55% stage 2, 9% stage 3+4, 19% REM.
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What can you conclude from this?
Lot of REM in babies can explain huge neuron dev., processing lots of info, dev. of motor/cognitive processes. Reduction of NREM w/ age implies the need for their functions declines w/ age- alzheimers sufferers drop NREM dramatically.
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Evaluate Ohayon's study.
+meta-analysis: accounts for ind. diff's, large sample size, ethical, supports restoration theory. -cause&effect diff to establish, extr vari's: presence of EEG, meta-analysis unreliable.
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Other cards in this set
Card 2
Front
What type of rhythm is the sleep-wake cycle, and what type of rhythm is the cycle WITHIN our sleep?
Back
Circadian Rhythm (takes place over 24 hours) and within sleep is an Ultradian Rhythm (cycle less than 24 hours- 90 minutes).
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