Donaldi Panildi, ago 13, Spokane, Washington for`his question‑.
What exactly is sleep?
When you finish a hard game, you need to rest a while. Your muscles arc tired and the heart needs time to pump in a supply of oxygen to refresh them. A11 animals, from the simplest to the most complex, need to rust after this kind of muscle fatigue. But not all animals need sleep ‑ for example, you will never catch a goldfish napping, The brains and nervous systems of the lower animals are far more simple and most experts believe that this is why they do not need sleep. They agree that sleep is necessary to oar sensitive, highly developed brain cells and nerve cells,
On just about every other matter concerning sleepy the experts are in disagreement. Also one can prove for sure either how we go to sleep and awake up or what exactly happens to refresh us during sleep. We can only offer theories, which are good ideas without facts to prove them.
During our waking hours, the sensitive nerve cells are bombarded with a million sensations, myriad impressions. One theory suggests that at the end of the day they have used up all their energy, somewhat as the muscles use; urn all their energy during a hard game. Sleepy according to this theory, is merely Nature’s way of giving the nerve cells time to rest and replenish themselves.
Another theory suggests that the chemical activity of the nerve: cells makes sleep necessary. The highly developed cells arc so active that they produce waste materials factor than they can got rid of them, These wastes clog the nervous system and sleep slows down the activity until things can be restored to normal.
There; is also disagreement as to how we drop off to sleep and wake up again. Ono theory suggests that sleep and not wakefulness is the natural state of the brain. We wake up only because vivid impressions such as hungers heat and emotional problems prod us out of remaining asleep. This theory claims that there is a wakefulness center in the brain which tries to block off these impressions.‑ we fall asleep only when it is able to shut out the impressions of daily life.
An opposite theory suggests that sleep is caused by an entirely different brain center. Then this center becomes tired it squeezes a set of blood vessels shutting off supplies to the brain. According to this the nervous system slows down to the level of sleep for lack of food. We wake up when this brain center has rested enough to let a fresh supply of blood flow into the brain.
All this adds up to two indisputable facts. Science does not yet understand the mysteries of sleep. Also, a good night's sleep is necessary to the good health of each and every one of us.