About 30 million people in the U. S. suffer from insomnia. It can be caused by a variety of things: overactive thyroid gland; diabetes; violent muscle twitching; drinking caffeine-containing beverages before going to bed; and painful arthritis.
It can also be caused by endocrine disturbances; by the use of certain chemical substances or by the withdrawal from others (including alcohol); by psychological problems such as anxiety and depression; and by disturbances in biorhythm, such as jet lag. However, experts estimate that in three-fourths of all cases the cause is a psychological one. After anxiety-producing events such as the death of a loved one or loss of a job, a person may experience sleep difficulties, for awhile. Many persons recover their normal sleep rhythm spontaneously, but others become frustrated and depressed and develop chronic insomnia. Napping during the day may throw off the sleep pattern further. Insomnia is not an illness that can be cured by a sleeping pill.
Sleeping disorders are usually divided into three kinds. The first kind are the Insomnias, which are a group of problems producing difficulty in falling asleep or difficulty in staying asleep. The second is hypersomnolence, characterized by too much sleep, or sleepiness when a person does not want to sleep. The third is episodic nocturnal events, disorders such as night terrors, nightmares, and sleepwalking.Bibliography: