Sleep is one of nature’s greatest inventions and blessings of life. It is a periodic rest of the body which is absolutely essential for its efficient functioning. It has been called the ” most cheering restorative of tired bodies. “
Sleep is an indispensable condition for the recuperation of energy. We go to bed fatigued and get up refreshed. Sleep repairs the wear and tear of the body and mind incurred during waking hours. Nothing is so restorative to the nerves as sound and uninterrupted sleep. Sleep is thus a vital element in a total way of life. It is a basic need in man’s mental as well as physical life.
During sleep, most of the functions of the body are carried on at the lowest level possible in health. Heat production is from 10 to 15 per cent below the basal level. The mechanism regulating the body temperature is less sensitive than in the waking state and is depressed by 0.5 to 1.0 degrees F. The rate of heart is reduced by 10 to 30 beats per minute and a decline in blood pressure of about 20 mm occurs in quiet restful sleep. The urine volume is considerably reduced, but its concentration in solids is increased. The tone of all the skeletal muscles is lessened. The eyes are usually rolled upward and the pupils constricted.
Loss of sleep exerts seriously detrimental effects on the nervous system. Long periods of wakefulness may cause profound psychological changes such as loss of memory, irritability, hallucination and even schizophrenic manifestations. During the last World War, prisoners in Nazi concentration camps who were kept awake for days by strong lights and blaring wireless sets collapsed.
Sleep versus rest
For correct living, it is essential to differentiate between sleep and rest. At rest, the body is disturbed by all exterior noises, but in sleep, it is screened from them by partial loss of consciousness and also by what is called ” dream protection. ” One useful purpose of the dream is to convert outside noises that might awake the sleeping person, into fantasies that do not disturb him.
During rest the limbs are normal, but in sleep, they swell. Blood flows from the brain, distends the arteries, and makes the limbs bigger. IN sleep more muscles are relaxed than in rest, though the sleeping person changes his position about 35 times in one night, without knowing it. Many organs which work during rest suspend their activities in sleep. Thus the recouping value of sleep is much more than that of rest or simply lying down.
Theories of sleep
Many theories of sleep have been advanced to explain the temporary loss of consciousness which we know as sleep. The oldest theory is that sleep is induced by a reduction in the blood supply to the brain or at least to conscious centres. This is known as the ischemic theory. Even the ancient Greek physicians were aware that the carotid artery was in a way concerned with the onset of sleep. The name itself expresses this belief. The Greek word ‘ Karotides’ for carotid arteries is derived from karoo which means ‘put to sleep.’ In modern times, the drowsiness after a meal, presumably due to the diversion of blood from the brain to the digestive organs, is cited in support of the ischemic theory.
Another important theory about sleep is the chemical theory. As a result of experiments on the metabolism of sleeping subjects, it is considered that fatigue-inducing sleep may be a mild form of blood poisoning or toxaemia. This ” poisoning” is believed to be brought on by energy expenditure during waking hours.
According to this theory, every contraction of a muscle and every impulse passing through the brain or the nerves breaks down a certain amount of tissue. The debris from broken down tissue is then thrown into the bloodstream. In the waking state, much of the waste from broken down tissue is got rid of through the natural eliminating processes of lungs, kidneys, bowels and skin.
But there comes a saturation point when there is such an accumulation of waste that it cannot be disposed of by these processes and it then invades the grey matter of the brain. In such an eventuality, mental and physical alertness are impaired. It is nature’s warning that the waste product must be reduced to replenish the lost energy. So we get tired and the urge to get sleep becomes irresistible.
During sleep, the cells and tissues that break down to produce toxic waste become less active and the production of toxic waste is vastly reduced. Simultaneously, constructive activities take place within the body during sleep, which rebuilds the broken-down tissue.
Another theory places a sleeping centre in the hypothalamus. Many of the bodily changes in sleep such as the constriction of pupils, reduced frequency of heartbeat, and increased gastric tone and secretion are manifestations of the activity of hypothalamus nuclei, especially parasympathetic centres. Perhaps some of the sleeping pills affect this centre in the brain.
Although the various theories have a certain amount of experimental evidence to support them, none has really solved what is the most mysterious process in our lives. All we know is that sleep substitutes constructive measures for the destructive processes of our waking hours. We cannot live without sleep.
Sleep duration by age
Another mystery about sleep is that no two persons need the same amount of sleep. Dr Nathaniel Kleitman, Associate Professor of Physiology at the University of Chicago, who conducted years of extensive experiments at the University’s “Sleeping Laboratory” says that there is no more a normal duration of sleep than there is normal height and weight.
A study of 25 subjects spread over thousands of nights showed that the average amount of sleep needed to feel well rested is seven-and-a-half hours, though individuals varied from six to nine hours.
According to Dr Demmis Williams, a noted authority on sleep, the amount of sleep needed for an individual’s well-being, is determined by what he feels he needs, not by what other people, including the doctor, think is reasonable.
Below is a table showing the recommended hours of sleep by age group;
|Age Group||Hours of sleep needed|
|New Born; birth to 3 months age||14 – 17 hours|
|Infant; 4-12 months||12-16 hours|
|Toddler; 1-2 years||11-14 hours|
|Preschool; 3-5 years||10-13 hours|
|School Age; 6-12 years||9-12 hours|
|Teenagers; 13-18 years||8-10 hours|
|Adults||7-9 hours (Individuals vary)|
The depth of ordinary restful sleep fluctuates throughout the sleep. In most adults, sleep deepens through the first hour, after which it lightens rather sharply and then more gradually until morning or until the usual time of awakening. In growing children, however, sleep deepens a second time for a little while. According to Dr Lindlahr, a famous naturopath, two hours before and two hours after midnight are the most valuable for sleep all the twenty-four hours of the day. In these four hours, mental and physical vigour are at their lowest ebb and sleep is soundest and most natural.
It is believed that three-quarters of our sleep consists of what is called ‘ slow wave sleep.’ The restorative processes occur during this time. The remaining quarter is taken by what is called ‘rapid eye movement (REM) sleep.’ It is also called paradosical or dreaming sleep and comes in episodes of about 20 minutes duration about five times a night. It involves dreaming, irregular heart rates, raised blood pressure and erection of the penis. It is in this phase of sleep that normal healthy young men may have wet dreams. Both forms of sleep are considered equally important, being normal sleeping rhythms.
There are many theories about good and bad sleeping positions. Practically everyone changes positions several times during sleep. Hence how one starts out is of no consequence. It is a good thing we do turn about in our beds. If we did not, we would awake in the morning stiff, having maintained the same position all night. For proper sleep, however, one should not sleep on one’s back but on the side with one or both legs brought well up and the head and the shoulder slightly forward.
Sleeping pills and habits
Sleeping pills are no (long term) remedy for sleeplessness. They are habit-forming and become less effective when taken continuously. They lower the I.Q. dull the brain and can prove fatal if taken in excess or before or after alcohol. The side-effect of sleeping pills includes indigestion, skin rashes, lowered resistance to infection, circulatory and respiratory problems, poor appetite, high blood pressure, kidney and liver problems and mental confusion.
Sleeping well is an art. It needs a perfect blend of healthy habits and control of the mind. A clean body and mind, relaxed mood, physical exercises, and perfect dietary control are some basic sleep-inducing methods.
Unpleasant situations at bedtime such as arguments, quarrels, watching a horror movie, or listening to loud music which would create anxiety, fear, excitement and worries should be avoided. Such situations stimulate the cerebral cortex and tend to keep one awake.
The sleeping place should be well ventilated, with a balanced temperature and free from noises. The bed should be neither too hard nor too soft, but comfortable. The pillow should not be too hard or too high. The bed clothes should be loose-fitting and light-coloured. Another important rule is not to have heavy food shortly before bedtime.