Allen Johnson, age 13, of Lansing, Mich., for his question
HOW DOES SLEEP COME ABOUT?
All human beings must have a certain amount of daily sleep at regular intervals. As a person gets ready for that period of rest called sleep, his muscles relax and his heartbeat and breathing rate slow down. Slowly, he becomes unaware of what is happening around him.
Scientists have studied sleep, using an instrument called an electroencephal ograph. They have found that a person's brain gives off electric waves. The brain of an awake, relaxed person gives off about 10 small waves a second. Fewer waves are given off during sleep.
As a person falls deeply into sleep, his brain sends out slower but larger and larger waves. The slowest, largest waves occur during the first two or three hours of a sleep period.
During slow wave sleep, mental activity slows down but does not stop. Persons awakened from slow wave sleep can often recall unclear thought that they had while asleep.
A person's sleeping pattern develops gradually. A baby will sleep for brief periods of time but by the age of two or three months, the infant will learn to sleep through the night and will nap during the daytime.
By the time a child is about 6 years old, he most likely will have given up his daytime naps.
Four year old children usually average between 10 and 14 hours of sleep each night, while a 10 year old will probably average between nine and 12. Most adults will sleep between six to nine hours each night.
Scientists do not know exactly how sleep restores vigor to the body, but it does.
A sleeping person changes the position of his entire body at least a dozen times during an eight hour period of sleep. He will move his head, arms and legs more often.
During an eight hour period of sleep, the average person dreams for about 100 minutes.
If a person doesn't get his sleep, he quickly loses his energy and can become quick tempered. After two days without sleep, he will find that lengthy concentration is very difficult and that he can be easily distracted.
People who go without sleep for more than three days have great difficulty thinking, seeing and hearing clearly. They also have periods of hallucinations during which they see things that do not really exist.
In medical studies, people have gone for as long as 11 days without sleep. People in this experiment lose all contact with reality.
Sleep definitely restores energy to the body and particularly to the brain and nervous system.