Outline9f09 - Outline 9: SLEEP I. The Sleep Cycle in short:...

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1 Outline 9: SLEEP I. The Sleep Cycle in short: "Initial" stage 1 slow wave sleep REM sleep Some Brain Waves (EEG's) "Beta" waves - present when we're alert and awake, brain waves are fast (high frequency, desynchronized, low amplitude waves) Alpha waves - present when we are awake but relaxed and just before sleep, brain waves slow down (larger amplitude, lower frequency waves) Delta waves - present during "slow wave sleep" very slow (low frequency) high amplitude waves Humans: Stage 1 -"hypnogogic" Stage 2 - "sleep spindles and K complexes" Stage 3, dropped blood pressure and body temperature, Delta waves Stage 4 , Deep Sleep- Delta waves predominate 3 2 REM sleep 2 3 4 3 ... Night time sequence: Stage 1, 2, 3, 4, 3, 2 ( = 50-90 min.), REM (10-20 min.), Stage 2-4-2, REM. .. REM to slow wave sleep cycle repeats about 3-5 times per night As the night progresses, REM time per cycle increases slightly and deep sleep decreases.
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REM sleep -Defined, literally, by the presence of rapid eye movements -Time of dreaming -Found in placental and marsupial mammals (Does this mean that non-REM species like the spiny anteater don't dream?) -EEG characteristic wave forms are similar to awake states -Powerful inhibition of motor neurons involved in movements of the extremities -Brain stem neurons are highly active creating diffuse activation of cortical regions -Changes with age- a greater proportion of time spent in REM sleep in babies II. Some brain regions involved in sleep- 1. Regions of the reticular formation some are involved in maintaining wakefulness Discrete regions of the caudal reticular formation are important for different aspects of REM 2. Raphe nucleus - lesions here in cats produce insomnia 3. Basal forebrain - lesions here reduce sleep in cats Questions: Why do we sleep? Why do we dream? III. Why do we sleep? A. The major theories: Circadian theory (closely related to the evolutionary theory of sleep) - We sleep to keep us out of trouble and conserve energy (like hibernation) The evolutionary theory of sleep predicts that sleep time should be related
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Outline9f09 - Outline 9: SLEEP I. The Sleep Cycle in short:...

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