What you didn’t know about sleep | Sunday Observer

What you didn’t know about sleep

In plain language, sleep means absence of wakefulness. According to some authorities, sleep is a state of physical and mental activity from which a person can be aroused. A healthy adult usually sleeps for about seven hours a day. Depending on the age and physical and mental fitness, the number of hours may vary. Sometimes, we hear about people who sleep only for about three or four hours a day. There are some abnormal people who have not slept for years. Medical experts say we spend one-third of our lives in sleep. However, most of us know very little about the subject.

Sleep is a requirement for normal functioning of the human body. We require some rest and relaxation to revitalize our bodies. Although scientists are unable to say how much sleep is necessary for the body, total sleep deprivation may result in death. Most of us consider sleep as a time of tranquillity to set aside the tensions of the day and spend the night in uneventful slumber. However, a good deal of activity occurs throughout the night.

Much of our knowledge of what happens during sleep comes from the electroencephalogram (EEG), a measurement of electrical activity in the brain. Instruments that measure muscle and eye movements also reveal a good deal of physical activity during sleep.

According to psychologists, there are five stages of sleep. During the first stage there are rapid, low amplitude brain waves. This lasts only for a few minutes. When you enter stage two, it is characterized by a slower and more regular pattern. It is difficult to awaken a person during this stage. When you drift into stage three, the brain waves become slower with higher peaks and lower valleys in the wave pattern. Stage four sleep occurs during the early part of the night. Dreams occur during the fifth stage. We know that children sleep more than adults. Similarly, infants sleep more than children. Most infants sleep for about 16 hours a day, but adults usually sleep for about seven hours a day.

Growth hormone

Sleep is necessary for the growth and restoration of damaged or worn-out body tissues. According to medical opinion, in children growth hormone is released during sleep. Even in adults similar restorative substances may be released during sleep to repair worn-out body tissues. Therefore, everybody needs a good night’s sleep. Medical researchers use what is known as the electroencephalogram (EEG) and the electro-oculogram (EOG) to study what happens when a person sleeps.

The EEG records the brain’s electrical rhythms and the EOG records the movements of the eyeballs. These are usually recorded during sleep by fixing electrodes on the scalp and face of the subject before he goes to sleep.

Scientists say, the brain’s electrical rhythms change during sleep. Based on the types of electrical reflexes, sleep is divided into two varieties: Orthodox and Paradoxical sleep. In Orthodox sleep there is Non-Rapid Eye Movement (NREM) and the subject does not see dreams. Rapid Eye Movement (REM) takes place during Paradoxical sleep or dreaming sleep. During REM sleep the eyeballs make jerky movements behind closed eyelids. During this stage the blood pressure and nervous activity increase.

Therefore, technically sleep is not a peaceful state. In the past people believed that dreamless sleep was the best. However, today it has been established that most of us see dreams during sleep. Some of us can recall our dreams vividly, but others fail to do so. When a person wakes up in the middle of a dream, he can remember it. When he wakes up after the dream he may or may not remember it.

Sleep has its own cycles. At first we fall into NREM sleep. After some time we enter the second cycle known as REM sleep. The sleep cycles are necessary for the body. Unfortunately, some people find it difficult to sleep. Doctors say they suffer from insomnia.

Some of those who suffer from this malady find it difficult to sleep. Others go to sleep at once but awaken after a few hours. There are others who sleep well most of the night but awaken too early in the morning. For all such problems doctors advise patients to avoid daytime naps. They also recommend moderate exercise before bedtime. Sometimes, patients are advised to avoid mental activities such as late night studies. In the meantime, yoga exercises and meditation before bedtime have been found to induce sleep.

Heraclitus

Philosophers and celebrated authors have commented on sleep in their own inimitable way. The celebrated Greek philosopher Heraclitus (c.600-c.540 BC) who said everything is in a state of flux, or change, and war and strife between opposites is the eternal condition of the universe concluded, “The waking have one common world, but the sleeping turn aside each into a world of his own.”

Leigh Hunt (1784-1859), the English poet and essayist, said, “There is, perhaps, no solitary sensation so exquisite as that of slumbering on the grass or hay, shaded from the hot sun by a tree, with the consciousness of a fresh light air running through the wide atmosphere, and the sky stretching far overhead upon all sides.” I find what Thomas Wolfe (1900-1938), the American writer, said even more entertaining and memorable than the quotations of the other two celebrities. He said, “Sleep falls like silence on the earth, it fills the hearts of ninety million men, it moves like magic in the mountains and walks like night and darkness across the planes and rivers of the earth, until low upon lowlands and high upon hills, flows gently sleep, smooth – sliding, sleep – oh, sleep – sleep – sleep!”

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