the Stuff of Dreams
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.
Speculations about its nature have been going on for literally thousands of years, and an 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.
Rest, in terms of muscle relaxation and so on, can be achieved by a brief period lying, or even sitting down.
The body's tissues are self-repairing and self-restoring to a degree, and function best when more or less continuously acitve. In fact, a basic amout of movement occurs during sleep which is specifically concerned with preventing the muscle inactivity.
If it is not a question of resting the body, perhaps it is the brain that needs resting. This might be a plausible hypothesis were it not for two factors.
First the electoencephalograph (which is simply a device for recording of the electrical activity of the brain by attaching electrodes to the scalp) 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.
The second factor is more interesting and more fundamental.
In 1960 an American psychiatrist name William Dement published experiments dealing with the recording of eye-movements during sleep.
He showed that the average individual's sleep cycle is punctuated with bursts of eye-movements, some drifting and slow, others jerky and rapid.
People woken during these periods of eye-movements generally reported that they had been dreaming. When woken at other times they reported no dreams.
If one group of people were disturbed from their eye-movements sleep for several nights on end, and another group were disturbed for an equal period of time but when they were not exhibiting eye-movements, the the first group began to show some personality disorders while the other seemed more or less unaffected.
The implications of all this were that it is not the disturbance of sleep that mattered, but the disturbance of dreaming.
on end 持续地
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