Sleep is a bodily need that takes up about one third of Iife-span. After a whole day's toil, both brain and body get tired. Sleep is necessary to restore energy and freshness to the tired organs and tissues of our body. It enables the body to repair worn out tissues and cells.
Do you know how sleep comes to us and what happens to our body during sleep? According to scientific facts, there is a very complex area in the brain called "sleep centre". Calcium ions present in the blood, control this centre. When an optimum quantity of calcium is received by the "sleep centre", we get sleep. It has been observed from experiments on animals that they start sleeping when calcium is injected directly into the sleep centre. But if calcium is injected into the blood stream, this does not happen. During sleep, the sleep centre does two things. Firstly, it blocks off the brain so that we have no willpower or consciousness left and secondly, it blocks all nerves leading from the brain so that our internal organs and limbs fall asleep.
In sleep, our body continues doing many types of movements. A man on 'an average changes his side’s 20 to 40 times during sleep in one night. Blood circulation continues during sleep. Heart beat slows down a little bit. The digestive system works normally. Liver and kidneys perform their functions. The effect of sound, light, heat, smell etc. in sleep are the same on every sleeping person. During sleeJ3r the body temperature is lowered by about one degree centigrade and the body cells are quietly engaged in getting rid of waste materials that have accumulated during the active part of the day.
How many hours a healthy person should sleep? The number of sleeping hours needed varies with individuals. The average adult needs from 7 to 9 hours of sleep. Boys and girls of 15 years of age need about 10 hours sleep each night. It is wise to form the habit of going to bed at the same time each night. Insomnia is the condition in which a person has difficulty in falling asleep. Such sleeplessness is often associated with pain, but worry can also keep a person awake. A dark, quite room that is well ventilated and cool is good for sound sleep.