lecture14 - 1 Sleep researchers have discovered 5...

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2 Sleep researchers have discovered 5 distinctly different stages of sleep, based on physiological recordings. Stage 1 is a brief, transitional stage of light sleep that lasts between 1 and 7 minutes. The EEG moves from predominately alpha waves, when the person is just about to fall asleep, to more theta activity. Hypnic jerks, those brief muscle contractions that occur when one is falling asleep, occur in stage 1 sleep. Stage 2 is characterized by more mixed brain wave activity with brief bursts of higher-frequency brain waves, called sleep spindles. Stages 3 and 4 are characterized by low frequency delta waves. It takes about 30 minutes to reach stage 4, and usually people stay there for about 30 minutes. Then the cycle reverses. When stage 1 should be next in line in the cycle, something interesting happens…rapid eye movement (REM) sleep begins. REM sleep was accidentally discovered by Nathaniel Kleitman in the spring of 1952 – see chapter opening story. REM sleep is characterized by an EEG that looks awake and alert…and by rapidly moving eyes behind the lids, an irregular pulse and breathing rate, and loss of muscle tone. When someone is awakened from REM sleep, they report vivid dreaming. Infants spend much more time in REM than do adults. During adulthood, sleep
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This note was uploaded on 04/13/2010 for the course CA 1001 taught by Professor James during the Spring '06 term at Buffalo State.

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lecture14 - 1 Sleep researchers have discovered 5...

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