SLEEP DISORDERS
Partly as a result of such changes in sleep, sleep problems become more common as people age. Sleep
disorders, however, can occur throughout life.
Childhood
disorders Infants may fail to sleep through the night during the first year of life. If not treated, such sleep disturbances sometimes continue into early childhood. Common causes include physical illness, inconsistent responses to awakenings (promptly tending to the child on some nights but letting it cry on others), and fears at night of which the parents are unaware. For example, children may confuse sleep with death.
Between five and seven years of age some children scream out in the night and appear terrified. During such "night terrors" they do not respond to efforts to comfort them until they fully awaken several minutes later. Once awake, these children may describe a frightening image but not a storylike dream or nightmare. Night terrors usually arise from deep NREM sleep within the first two hours of the night. They may represent an abnormal, partial awakening. True nightmares have vivid images and a plot. They usually arise during REM sleep during the later hours of the night. Other childhood sleep disorders include bed-wetting and sleepwalking.
Adolescent Disorders
Several sleep disorders may arise during adolescence. One disorder, called the delayed sleep phase syndrome, is present when a young teenager has nightly
difficulty falling asleep until 3 to 4 am or later. The affected person sleeps normally when allowed to sleep from late in the night until late in the day (1 to 2 pm). The disorder is caused by a biological clock that "beats" too slowly. The clock cannot be set back, but it can be set forward, so that delaying sleep by several hours a day eventually results in a normal schedule that can be maintained by keeping regular hours.
Another disorder that arises during adolescence is narcolepsy.The hallmark of narcolepsy, which can also arise in the middle years of life, is the inability to remain awake for longer than several hours. Affected people may also experience brief bouts of weakness (cataplexy), which may cause them to fall to the ground when they experience laughter, anger, or other strong emotions. Certain prescription drugs are used to control this condition.
Disorders of Adulthood and Old Age
The sleep disorders of childhood occasionally persist or return during adulthood, including night terrors and sleepwalking. These may be side effects of medications or alcohol. Older people may not lose muscle strength as normally occurs during REM sleep, and dreams are then "acted out." Injuries may occur as the dreamer strikes out at or runs from an imaginary opponent.
Travelers and shift workers can have difficulties falling asleep, a phenomenon known as "jet lag." Both stem from attempting to sleep at times that are at odds with the internal biological clock. Excessive daytime sleepiness can be a chronic and disabling problem. It may be caused by sleep deprivation, by sedative medications, by narcolepsy, or by a breathing disorder called sleep apnea.
A condition called "restless leg syndrome" may also arise. This uncomfortable urge to move the legs develops in sedentary situations, especially in the evening. The feeling is characteristically relieved by walking or other leg movements, but in turn delays sleep. When the person finally does fall asleep, periodic leg movements and brief awakenings occur.
Worry and anxiety can delay sleep for only a few nights at a time but bouts may recur often. Difficulty in remaining asleep can result from depression and from painful illnesses or breathing difficulties. Insomnia includes difficulty in falling asleep, difficulty in maintaining sleep through the bed-rest period, and a sense of not having slept well. It is often perpetuated by spending more time in bed than can be filled with sleep or by varying the bed-rest period. Bed-rest periods should not be longer than needed,because the amount of sleep is regulated by the brain, not by time spent in bed.
Prescription and nonprescription sleeping pills are sold to aid sleep. Such drugs speed the onset of sleep and reduce the tendency to awaken during the night, but these benefits tend to lessen with time. The drugs may not greatly improve sleep if the underlying cause of the problem has not been treated, and they also may lead to dependency.
Sleep-disorders medicine has grown, with centers for diagnosis and treatment now located throughout the United States. Most centers have laboratories where patients can sleep for a night for diagnostic recording of their sleep, breathing, heart function, and body movements.