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.When we first fall asleep, most of us start with the orthodox variety and only change to paradoxicalsleep after about two hours.If an experimenter monitors a subject constantly and wakes him everytime he start to show rapid eye movements, then a state of deprivation builds up and the subject tendsto start right away with paradoxical sleep as though determined to make good the deficit.It seems thatboth kinds of sleep are equally important, but for different reasons.We tend to think of bodies as relatively permanent structures, but individual cells have a very shortlife and are continually being replaced, not just on the skin and in the gut lining, where they arerubbed away by friction, but even in the bones.Friends may look unchanged to you after longabsences, but if several years have elapsed there will not be a single cell present that was there lasttime you met.Regeneration and replacement depend on the synthesis of new protein, and most of thisseems to take place during sleep.In orthodox sleep it seems that the body tissues are most affected;after strenuous athletic days, people spend more than the usual amount of time in orthodox sleep.Human growth hormones are manufactured during this time, and the rate of cell division increasessoon after falling asleep.The tissues of the brain differ from those of the rest of the body in that they stop growing after acertain age and concentrate largely on repair and maintenance.Most of brain growth occurs during thetwo months just before birth and the month after it.In this time the cortex of gray matter is produced,and the baby not only sleeps twice as long each day as the normal adult, but it also spendsproportionally twice as much time in paradoxical sleep.It seems that, while the body is repaired inorthodox sleep, the brain receives attention in the alternate periods, when more blood flows to thehead and more heat is generated there.As soon as it was discovered that the rapid eye movements of paradoxical sleep were a sign ofdreaming, the idea grew that there might be some correspondence between these and body movementsand the content of the dream.(234) Active dreams seem to involve more movement, but it is unlikelythat the eyes are actually moving to look at dream pictures, because men who have been blind frombirth show exactly the same behavior in their dreams.Recordings of heart and breathing rate, bodytemperature, pulse wave, and skin potential show that these vary directly with the emotional contentof the dream, so it is nevertheless a very real experience.Analysis of dream content shows that they do not necessarily form a continuing story that runs inepisodes throughout the night, but they do tend to start off with a subject related to the experiences ofthe previous day before shifting to earlier periods of life.This has given rise to the theory that dreamshelp a person assimilate the events of the day by rerunning some of them and comparing them withprevious experience before filing the lot away in the memory banks.It fits in with the fact of dreamdebt building up, presumably because of the pressure of unsorted experience accumulating in thecortex.There is in fact strong electrical activity during paradoxical sleep in the very area just belowthe cortex that is thought to be the site of the memory.The symbols in dreams seem to be the direct action of the unconscious, censoring and shaping imagesto suit its own purpose.Freud based his system of psychoanalysis largely on dreams.Hisinterpretations were sometimes a little simplistic and are not followed rigidly today, but he seems tohave been right in assuming that the unconscious was not amenable to direct investigation and couldonly be examined at second hand by inference.His emphasis on the sex drive is sometimes criticisedas an exaggeration based on the minds of the frustrated young women of nineteenth-century Vienna,but it has been vindicated somewhat by Calvin Hall in a recent study.(234)Hall made lists of all the dream objects that psychoanalysts took to be symbolic of the male sex organand came up with 102 symbols for penis, including stick, gun, pen, rod, dirk, etc.Then he wentthrough Partridge's Dictionary of Slang and found that all of these, plus another ninety-eight theanalysts had never thought of, had been in use as coarse English descriptions of the phallus forhundreds of years.There is constant argument about whether animals dream.Many of them go through movements thatlook like patterns of hunting and feeding while they sleep, but these usually take place duringorthodox sleep even in those animals that also have paradoxical periods.Cats, dogs, chimps, andhorses all have alternating periods of both kinds of sleep, but it will probably never be possible to sayfor certain whether they actually dream in one or the other.It seems likely, though, that the two sleeppatterns serve the same restorative functions for these species as they do in man.In cats paradoxical sleep occurs throughout life, but in many apparently less intelligent animals it canbe found only in very young individuals.Sheep and cows show signs of both states of sleep beforeweaning, when their brains are still growing, but later the paradoxical patterns disappear altogether.Inspecies such as raccoons and monkeys, which are much more inventive and aware, there are strongindications of paradoxical, rapid-eye-movement sleep at all ages.There seems to be a directcorrelation between this kind of sleep, which is closely associated with dreaming, and a high level ofconsciousness.A survey of the animal kingdom therefore shows a gradation of awareness.At the lowest levels organisms are either active or inactive, but in more advanced species andparticularly among birds and mammals, the period of inactivity takes on special active functions of itsown.In the most complex animals it is even divided into two different kinds of sleep, associated withseparate physiological and psychological processes.And now, in man, it seems that there is an extrastep, one that has given rise to a new kind of awareness.This new development is highlighted by chemicals that produce changes in behavior.Drugs can bedivided into several broad categories on the basis of the kind of change they make.The first group arethose, such as the amphetamines, cocaine, and caffeine, which stimulate metabolism; in biologicalterms we must consider these as being similar in action to the reticular system of the brain, whichproduces wakefulness.The second group have the opposite effect; these are the barbiturates andtranquilisers, which act as sedatives and are biologically equivalent to the process producingsleepiness, but the interesting thing is that they result only in orthodox sleep [ Pobierz całość w formacie PDF ]