the restoration theory. The conservation theory proposes that we
basically need to sleep in order to preserve our energy for our
daytime use. When our use of energy amount is considered in terms of
the rate of metabolism, slow wave sleep especially the first four
stages spends merely 5 to 25 % of the amount we use during day, and
slow wave sleep is strongly "associated with conservation of energy".
Another theory, the restoration theory, holds two hypotheses, the
whole body restoration and the neurological restoration. The whole
body restoration hypothesis suggests that sleep functions as a process
of "anabolism" with respect to protein as well as a release of more
hormones. The neurological restoration hypothesizes that brain is the
one that needs to sleep. In addition, each stage is responsible for
the partial brain restoration and that is why people need to repeat
several non REM and REM sleep cycles throughout the night. Some
researchers even hypothesize that these two theories might be both
correct, and the sleep function is still a myth.
Why do we sleep in the first place? What triggers to fall asleep is
not a single source. For example, it has been said that the
hypothalamus, located in the center of the brain, collects messages
from certain cells and carry the signal to the pineal gland in the
brain. This process causes to produce the "hormone melatonin" which
helps the body temperature to go down. Also, another example is raphe
nuclei, located in the part of the brain which is in charge of
"unconscious activity" such as walking and eating, sends an order to
nerve impulses to shut down the brain system. Therefore, falling
asleep is not merely a single process but a collective event
Many researchers have been trying to find out the functions and
symbols of dreams. Though there are many theories, researchers have
not exactly found out the reasons we dream and whether the contents of
dreams have directly something to do with our everyday life. The first
theory came up by a psychologist, Sigmund Freud. Freud explained that
what is in our dream is the "repressed longing": the suppressed
thoughts and desires that we are usually unable to express socially.
Carl Jung also supports Freudian ideas especially the origin of
dreams, but except for one important principle. What Jung sees
different is that dreams enable us to see ourselves as well as solve
our problems. The third theory, "activation-synthesis hypothesis",
proposed by Allan Hobson and Robert McCarley in 1970's takes a very
different view compared to Freud and Jung. They claim that dream
consists of random images which are stored as a memory in our head.
These random images, dreams, are created by "nerve signals sent out
during REM sleep from a small area called the pons" .Though there are
many theories to solve the representation of dreams, the recently
study in 1997 by Mark Solms using fMRI and PET seem to lean toward
Freudian theory. Solms studied people with a brain damage, and
concluded that the most active place during sleep was the part which
controls emotion regardless of the differences in brain damages.
Though many researchers including Solm do not necessarily see Freudian
ideas as completely valid, they do believe that unconscious thoughts
may be projected on our dreams.
REM sleep and dreams are related, but what is important about them? In
the study by William Dement at Stanford University School of Medicine,
participants were awaken when they were about to go to REM sleep
stage, and Dement concluded that many participants had a psychological
problem such as anxiety and irritability. According to this theory,
REM seems like an essential sleep stage for humans. Jerry Siegel,
director of UCLA's center for sleep research explains that "REM sleep
may have evolved for physiological reasons" considering that Non REM
and REM behave like the automatic temperature change which a lot of
animals do. Siegel also see dreams as a kind of "epiphenomenon" of a
sleep product. The importance and function of sleep and dreams are
controversial; some researchers claim that sleep and dreams are
essential for health whereas some claim that they were a necessary
development for human.
Although there has been many researches and theories on sleep and
dreams, we still have not found why we actually sleep and what exactly
the importance of this activity. After all, sleeping can be accepted
as a fact that we all have to do everyday in our life regardless of
the puzzles in reasoning. Because of the technological advancement,
our scientific discovery has been much more rapid. Someday, some
research might be able to find out the definite answers for sleep and
dreams, but until then, the myth of sleep and dreams remains with us.
No comments:
Post a Comment