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Lesson 19 |
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The stuff of dreams |
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What is going on when a person experiences rapid eye-movements during sleep? |
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It is fairly clear that the sleeping period must have some function, and because there is so much of it the function would seem to be important. |
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Speculations about its nature have been going on for literally thousands of years, |
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and one odd finding that makes the problem puzzling is that it looks very much as if sleeping is not simply a matter of giving the body a rest. |
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'Rest', in terms of muscle relaxation and so on, can be achieved by a brief period lying, or even sitting down. |
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The body's tissues are self-repairing and self-restoring to a degree, and function best when more or less continuously active. |
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In fact a basic amount of movement occurs during sleep which is specifically concerned with preventing muscle inactivity. |
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If it is not a question of resting the body, then perhaps it is the brain that needs resting? |
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This might be a plausible hypothesis were it not for two factors. |
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First the electroencephalograph (which is simply a device for recording the electrical activity of the brain by attaching electrodes to the scalp) |
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shows that while there is a change in the pattern of activity during sleep, there is no evidence that the total amount of activity is any less. |
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The second factor is more interesting and more fundamental. |
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Some years ago an American psychiatrist named William Dement published experiments dealing with the recording of eye-movements during sleep. |
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He showed that the average individual's sleep cycle is punctuated with peculiar bursts of eye-movements, some drifting and slow, others jerky and rapid. |
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People woken during these periods of eye-movements generally reported that they had been dreaming. |
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When woken at other times they reported no dreams. |
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If one group of people were disturbed from their eye-movement sleep for several nights on end, |
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and another group were disturbed for an equal period of time but when they were not exhibiting eye-movements, |
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the first group began to show some personality disorders while the others seemed more or less unaffected. |
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The implications of all this were that it was not the disturbance of sleep that mattered, but the disturbance of dreaming. |