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Sleep (Chemicals involved in sleep (Adenosine (Low levels of adenosine -…
Sleep
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Why do we sleep?
To allow --> brain to rest --> recover from mental exercise --> energy conservation --> consolidation of long-term memories --> for learning --> predator avoidance --> free radicals --> sleep to get rid of waste produced by brain during day
Recuperation theories --> being awake disrupts homeostasis --> internal physiological stability --> sleep is required for restoration --> sleep is terminated by return to homeostasis
Circadian theories --> sleep reaction to result of internal 24 hour timing mechanism --> programmed to sleep at night not day --> rather than a reaction to disruptive effects of wakefulness
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Free-running circadian sleep-wake rhythms --> circadian rhythms in constant environments --> duration --> varies in length per subject but is innate --> referred to as internal biological clock
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Homeostasis --> controls many things like body temperature --> hormone levels --> sleep --> wakefulness --> digestion
Learning theories -->sleep improves sequences of motor learning --> the lightest part of sleep --> stages 1 and 2 --> and sleep spindles
Declarative memories --> memories of past episodes of one's life --> relation to stimuli --> or word learning
Non-declarative memories --> memories gained through experience --> and practice --> e.g. driving --> playing piano....
Stages of sleep
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Stage 1:
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Theta activity: 3, 5-7.5 Hz
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Each cycle around 90 minutes --> after stage 4 goes to stage 1 again --> gradual increase in EEG voltage and decrease of frequency in the progress of stage 1 to 4
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Dreaming
Main beliefs --> external stimuli --> incorporated in dreams --> dream could run on real time --> only report dreams if awakened during REM sleep --> sleep talking occurs during any stage --> sleepwalking only occurs during slow-wave sleep --> REM dreaming --> vivid --> SWS dreaming --> thoughtful
Freud --> psychoanalytic interpretation --> dreams are wishes --> perhaps undesirable or unacceptable --> merely described version of real wishes --> latent dreams
Hobson --> activation-synthesis theory --> biological interpretation --> idea that REM sleep triggers changes in neural activity --> initiates brain stem --> suggested activity change creates content for REM sleep --> our dreams
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Reduced physical activity --> decrease in muscle responsiveness --> characterised by feeling of sleepiness --> desire to seek a comfortable place to lie