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Psychology 3325 Lecture Notes - Sleep Deprivation, Ryback, Cerebral Cortex

Course Code
Psychology 3325
John Usher

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Functions of Sleep
sleep is univeral behaviour
Indus dolphins live in mud and have become blind because vision is not useful very
dangerous for it to sleep and does not stop swimming but sleeps at 4-60 second intervals
= sleep must serve some important purspose or would have been eliminated as well
simplest explanation for sleep is that it serves to repair wear and taer on bodies caused by
moving and exercising
sleep deprivation studies has not provided evidence that sleep is necessary for body to
function normally
Horne reviewed more than 50 experiments in which humans had been deprived of sleep and
reported thta most of them found sleep deprivation did not interfere with people's ability to
perform physical exercise; also found no physiological stress response to sleep deprivation
studies suggest that sleep-deprived people are able to perform normally on most intellectual
tasks, as long as tasks are short perform more poorly on tasks tha require high level of
cortical functioning after two days of sleep deprivation, especially on tasks that require them
to be watchful, alert, and vigilant
during stage 4 metabolic activity of brain decreases to about 75% of waking level stage
gives brain a chance to rest
people are unreactive to all but intense stimuli during slow-wave sleep and if awakened
act groggy and confused as if cerebral cortex has been shut down and hasn't yet
resumed its functioning
suggest brain is indeed resting
studies on sleep deprivation in human suggest that brain needs slow-wave sleep in order to
recover from day's activities but rest of body doesn't
another way to determine whether sleep is needed for restoration of physiological functioning
is to look at effects of daytime activity on nighttime sleep
Ryback and Lewis found no changes in slow-wave or REM sleep on healthy participants
who spent 6 weeks resting in bed should expect them to sleep less
Adey, Bors, and Porter studied sleep of completely immobile quadrpilegics and paraplegics
and found only small decrease in slow-wave sleep as compared to others
bodily exercise has little effect on sleep but mental exercise seems to increase demand for
slow-wave sleep
Horne and Minard found way to increase mental acitbity without affecting physical activity
and without causing stress
told volunteers to show up for experiment to take some tests to assess reading skills but
when people showed up they were told plans have changed and they were invited for a
day out at expense of researchers
spent day visiting art exhibition, zoo, shopping centre, museum, amusement park and
watched movie driven from place to place and didn't become overheated by exercise
when they slept in labratory their slow-wave sleep particularly stage 4 was increased
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