Chapter 14 - Sleep, Dreaming and Circadian Rhythms

Chapter 14 - Sleep, Dreaming and Circadian Rhythms - SLEEP,...

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SLEEP, DREAMI&G and CIRCADIA& RHYTHMS (CHAP 14) Introduction to Circadian rhythms Animals generate cyclic behaviors that are regulated by internal clocks. However, we will see that these clocks can be reset or entrained by external stimuli, such as the cycle of day and night, or the tides. Endogenous cycles are advantageous because they often anticipate external changes Migration starts before winter Birds in cages show migratory restlessness Cycles can last about a year: circaannual : Hibernation: bats, ground squirrels, hamsters. Seasonal changes in reproduction, body fat Cycles can last about a day: Circadian. Sleeping and waking Temperature changes Hormonal changes, etc. All these cycles stay in synchrony, suggesting that there is a Master Clock Cycles are adapted to the movements of Earth. SLEEP The Physiological and Behavioral Events of Sleep. The Three Standard Psychophysiological Measures of Sleep. Data obtained by measuring : 1) The activity of the brain: electroencephalogram (EEG) 2) Movement of the eyes: electrooculogram (EOG) 3) Activity of neck muscles: electromiogram (EMG) Stages of sleep
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Sleep EEG ( stages distinguished using EEG) ( Fig. 14.2 ) : Alert wakefulness : Low amplitude, high frequency EEG waves: 13-30 Hz. Just before sleep, bursts of alpha waves appear (8-12 Hz). 4 stages of sleep EEG: STAGE 1 (Initial Stage 1): Low amplitude waves, frequency slower than alert wakefulness. STAGE 2: Amplitude of waves increases and frequency slows down. K complexes appear: single positive and negative wave. Sleep spindles appear: 1-2 sec burst of 12-14 Hz waves. STAGE 3: Amplitude of waves increases and frequency slows down. Delta waves appear occasionally: 1-2 Hz STAGE 4: Predominance of delta waves. Stages 3 and 4 are also known as slow-wave sleep (SWS). (ALSO CALLED REM SLEEP): Accompanied by: REM (rapid eye movements) Loss of muscle tone (Fig. 14.3) REM Sleep and Dreaming The observation that 80% of awakenings from REM sleep lead to dream recall provided evidence that REM sleep is the physiological correlate of dreaming. Only 7% of awakenings from non REM sleep stages lead to dream recall. Testing Common Beliefs about Dreaming. 1) External stimuli can become incorporated in dreams.
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2) Dreams run on “real time” 3) People who claim that they do not dream report dreaming if awakened in REM 4) Sleeptalking and Sleepwaking (somnambulism), and enuresis (bedwetting) occur least frequently during REM sleep (core muscles are relaxed), and most frequently in Stage 4 sleep. The Interpretation of Dreams Do dreams represent repressed wishes? Sigmund Freud: Dreams (manifest dreams) are disguised versions of our real dreams (latent dreams). Interpretation of dreams was important for exposing latent dreams and cure the patients.
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This note was uploaded on 04/04/2012 for the course PSYCH 202 taught by Professor Kim during the Fall '06 term at University of Washington.

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Chapter 14 - Sleep, Dreaming and Circadian Rhythms - SLEEP,...

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