Lesson 19 The stuff of dreams
It is fairly clear that sleeping period must have some function, and because there is so much of it
the function would seem to e important. Speculations about is nature have been going on for literall
y thousands of years, 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. 'Rest', in terms of muscle relaxat
ion 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 act
ive. In fact a basic amount of movement occurs during sleep which is specifically concerned with pre
venting muscle inactivity.
If it is not a question of resting the body, then perhaps it is the brain that needs resting? This m
ight be a plausible hypothesis were it not for two factors. First the electroencephalograph (which i
s simply a device for recording 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 evide
nce that the total amount of activity is any less. The second factor is more interesting and more fu
ndamental. Some years ago an American psychiatrist named William Dement published experiments dealin
g with the recording of eye-movements during sleep. He showed that the average individual's sleep cy
cle is punctuated with peculiar bursts of eye-movements, some drifting and slow, others jerky and ra
pid. People woken during these periods of eye-movements generally reported that they had been dreami
ng. When woken at other times they reported no dreams. If one group of people were disturbed from th
eir eye-movement sleep for several nights on end, and another group were disturbed for an equal peri
od of time but when they were no exhibiting eye-movements, the first group began to show some person
ality disorders while the others seemed more or less unaffected. The implications of all this were t
hat it was not the disturbance of sleep that mattered, but the disturbance of dreaming.