Chapter 9 - Chapter 9: Sleep and Biological Rhythms Why do...

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1Chapter 9: Sleep and Biological Rhythms Why do we sleep? •Restoration and recovery- of biochemical and physiological processes degraded during wakefulness -exercise does not make you sleep longer •energy conservation- 10% reduction in metabolic rate -blood pressure is reduced -respiration is reduced •memory consolidation- neuronal connections may be remodeled during sleep (at least for procedural/skill memory) A physiological and behavioral description of sleep •sleep cycle - 90 minutes •alpha activity: smooth electrical activity of 8-12 hertz recorded from the brain; generally associated with a state of relaxation •beta activity: irregular electrical activity of 13-30 Hz recorded from the brain; generally associated with a state of arousal •theta activity- occurs during stages 1 and 2 of sleep -EEG activity of 3.5-7.5 hz that occurs intermittently during early stages of slow-wave sleep and rem sleep Stage 1: transition between wake and sleep Stage 2: light sleep •characterized by theta activity Only present in stage 2 sleep: -sleep spindles: may represent periods where the brain is inhibiting processing to keep the sleeper in a tranquil state -K complexes: auditory response (knock at the door) •Also involved in sleep maintenance. More after sleep deprivation •Presumably protects the sleeper from awakening •delta activity: regular synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep REM sleep characterized by -eye movement -loss of muscle tone •REM sleep: a period of desynchronized EEG activity during sleep, at which time dreaming, rapid eye movements, and muscular paralysis occur; also called paradoxical sleep -narrative, story-like dreams •non-REM sleep -all stages of sleep except REM sleep •slow-wave sleep -non-REM sleep. Characterized by synchronized EEG activity during its deeper stages •electromyogram (EMG): an electrical potential recorded from an electrode placed on or in a muscle •electro-oculogram (EOG): an electrical potential from the eyes, recorded by means of electrodes placed on the skin around them; detects eye movements Stage 4: deepest stage of sleep
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-only loud noises cause a person to awaken -when awakened person is groggy and confused basic rest-activity cycle: a 90 minute cycle (in humans) of waxing and waning alertness, controlled by a biological clock in the caudal brain stem; controls cycles of REM sleep and slow- wave sleep REM sleep Vs. Slow-wave sleep EEG desynchrony (rapid, irregular waves) EEG synchrony (slow waves) lack of muscle tonus Moderate muscle tonus rapid eye movements Slow or absent eye movements penile erection or vaginal secretion Lack of genital activity dreams •alertness consists of desynchronized beta activity (13-30 Hz) •relaxation and drowsiness consist of alpha activity (8-12 Hz) Functions of Slow-wave sleep •sleep deprivation in humans -does not effect the ability to physical tasks -does effect the ability to perform cognitive tasks
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This note was uploaded on 03/30/2008 for the course PSY 454 taught by Professor Auger during the Spring '08 term at Wisconsin.

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Chapter 9 - Chapter 9: Sleep and Biological Rhythms Why do...

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