What Does Sleep Do For Us?
Although scientists are still trying to learn exactly why people need sleep,
animal studies show that sleep is necessary for survival. For example,
while rats normally live for two to three years, those deprived of REM
sleep survive only about 5 weeks on average, and rats deprived of all
sleep stages live only about 3 weeks. Sleep-deprived rats also develop
abnormally low body temperatures and sores on their tail and paws. The
sores may develop because the rats' immune systems become impaired.
Some studies suggest that sleep deprivation affects the immune system
in detrimental ways.
Sleep appears necessary for our nervous systems to work properly. Too little
sleep leaves us drowsy and unable to concentrate the next day. It also
leads to impaired memory and physical performance and reduced ability
to carry out math calculations. If sleep deprivation continues,
hallucinations and mood swings may develop. Some experts believe sleep
gives neurons used while we are awake a chance to shut down and repair
themselves. Without sleep, neurons may become so depleted in energy or
so polluted with byproducts of normal cellular activities that they
begin to malfunction. Sleep also may give the brain a chance to
exercise important neuronal connections that might otherwise
deteriorate from lack of activity.
Deep sleep coincides with the release of growth hormone in children and
young adults. Many of the body's cells also show increased production
and reduced breakdown of proteins during deep sleep. Since proteins are
the building blocks needed for cell growth and for repair of damage
from factors like stress and ultraviolet rays, deep sleep may truly be
"beauty sleep." Activity in parts of the brain that control emotions,
decision-making processes, and social interactions is drastically
reduced during deep sleep, suggesting that this type of sleep may help
people maintain optimal emotional and social functioning while they are
awake. A study in rats also showed that certain nerve-signaling
patterns which the rats generated during the day were repeated during
deep sleep. This pattern repetition may help encode memories and
improve learning.
Source: US NIH,
National Institute of Neurological Disorders and Stroke
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