Restless Legs Syndrome (RLS) Restless legs syndrome (RLS) causes an unpleasant prickling or tingling in the legs, especially in the calves, that is relieved by moving or massaging them. This sensation creates a need to stretch or move the legs to get rid of these uncomfortable or painful feelings. As a result, a person may have difficulty falling asleep and staying asleep. One or both legs may be affected. In some people, the sensations are also felt in the arms. These sensations can also occur with lying down or sitting for prolonged periods of time, such as while at a desk, riding in a car, or watching a movie. Many people who have RLS also have brief limb movements during sleep, often with abrupt onset, occurring every 5–90 seconds. This condition, known as periodic limb movements in sleep (PLMS), can repeatedly awaken people who have RLS and reduce their total sleep time. Some people have PLMS but have no abnormal sensations in their legs while awake. RLS affects 5–15 percent of Americans, and its prevalence increases with age. RLS occurs more often in women than men. One study found that RLS accounted for one-third of the insomnia seen in patients older than age 60. Children also can have RLS. This condition can be difficult to diagnose in children, and it often is confused with hyperactivity or "growing pains." RLS is often inherited. Pregnancy, kidney failure, and anemia related to iron or vitamin deficiency can trigger or worsen RLS symptoms. Researchers suspect that these conditions cause insufficient iron that results in a lack of dopamine. The brain uses dopamine to control limb movements. Doctors usually can diagnose RLS by patients’ symptoms and a telltale worsening of symptoms at night or while at rest. Some doctors may order a blood test for iron, although many people who have RLS have normal levels of iron in their blood but abnormal levels in the fluid that bathes their brain. Doctors may also ask people who have RLS to spend a night in a sleep lab where they are monitored to rule out other sleep disorders and to document the excessive limb movements. RLS is a treatable but not curable condition. Dramatic improvements are seen quickly when patients are given dopamine-like drugs. Alternatively, people who have milder cases may be treated successfully with sedatives or by behavioral strategies. These strategies include stretching, taking a hot bath, or massaging the legs before bedtime. Avoiding caffeinated beverages can also help reduce symptoms. If iron or vitamin deficiency underlies RLS, symptoms may improve with prescribed iron, vitamin B12, or folate supplements. Some people may require anticonvulsant medications to stem the creeping and crawling sensations in their limbs. Others who have severe symptoms may need to be treated with pain relievers, such as codeine or morphine, or a combination of drug treatments.
Narcolepsy Narcolepsy's main symptom is excessive and overwhelming daytime sleepiness, even after adequate nighttime sleep. In addition, nighttime sleep may be fragmented by frequent awakenings. People who have narcolepsy often fall asleep at inappropriate times and places. Although television sitcoms occasionally feature these individuals to generate a few laughs, narcolepsy is no laughing matter. People who have narcolepsy experience daytime "sleep attacks" that last from seconds to more than one-half hour, can occur without warning, and may cause injury. These embarrassing sleep spells can also make it difficult to work and to maintain normal personal or social relationships. With narcolepsy, the usually sharp distinctions between being asleep and awake are blurred. Also, people who have narcolepsy tend to fall directly into dream-filled REM sleep, rather than enter REM sleep gradually after passing through the non-REM sleep stages first. In addition to overwhelming daytime sleepiness, narcolepsy has three other commonly associated symptoms, but these may not occur in all people:
- Sudden muscle weakness (cataplexy). This weakness is similar to the paralysis that normally occurs during REM sleep, but it lasts a few seconds to minutes while an individual is awake. Cataplexy tends to be triggered by sudden emotional reactions, such as anger, surprise, fear, or laughter. The weakness may show up as limpness at the neck, buckling of the knees, or sagging facial muscles affecting speech, or it may cause a complete body collapse.
- Sleep paralysis. People who have narcolepsy may experience a temporary inability to talk or move when falling asleep or waking up, as if they were glued to their beds.
- Vivid (hypnogogic) dreams. These dreams tend to surface when people who have narcolepsy first fall asleep. The dreams are so lifelike that they can be confused with reality.
Experts estimate that as many as 350,000 Americans have narcolepsy, but fewer than 50,000 are diagnosed. The disorder is as widespread as Parkinson's disease or multiple sclerosis, and more prevalent than cystic fibrosis, but it is less well known. Narcolepsy is often mistaken for depression, epilepsy, or the side effects of medicines. Narcolepsy can be difficult to diagnose in people who have only the symptom of excessive daytime sleepiness. It is usually diagnosed with the aid of an overnight sleep recording (PSG) and the MSLT. (See "How Are Sleep Disorders Diagnosed?" on page 44.) Both tests reveal signs of narcolepsy—the tendency to fall asleep rapidly and enter REM sleep early, even during brief naps. Narcolepsy can develop at any age, but the symptoms tend to appear first during adolescence or early adulthood. About 1 of every 10 people who have narcolepsy has a close family member who has the disorder, suggesting that one can inherit a tendency to develop narcolepsy. Studies suggest that a neurotransmitter called hypocretin plays a key role in narcolepsy. Most people who have narcolepsy lack hypocretin, which promotes wakefulness. Scientists believe that an autoimmune reaction, perhaps triggered by disease or brain injury, specifically destroys the hypocretin-generating cells in the brains of people who have narcolepsy. Eventually, researchers may develop a treatment for narcolepsy that restores hypocretin to normal levels. In the meantime, most people who have narcolepsy find some to all of their symptoms relieved by various drug treatments. For example, central nervous system stimulants can reduce daytime sleepiness. Antidepressants and other drugs that suppress REM sleep can prevent muscle weakness, sleep paralysis, and vivid dreaming. Doctors also usually recommend that people who have narcolepsy take short naps (10–15 minutes) two or three times a day, if possible, to help control excessive daytime sleepiness. Parasomnias (Abnormal Arousals) In some people, the walking, talking, and other body functions normally suppressed during sleep emerge during certain sleep stages. Alternatively, the paralysis or vivid images usually experienced during dreaming may persist after awakening. These arousal malfunctions are collectively known as parasomnias and include confusional arousals, sleep talking, sleep walking, night terrors, sleep paralysis, and REM sleep behavior disorder (acting out dreams). Most of these disorders—such as confusional arousals, sleep walking, and night terrors—are more common in children, who tend to outgrow them once they become adults. People who are sleep-deprived also may experience some of these disorders, including sleep walking and sleep paralysis. Sleep paralysis also commonly occurs in people who have narcolepsy. Certain medications or neurological disorders appear to lead to other parasomnias, such as REM sleep behavior disorder, and these parasomnias tend to occur more in elderly people. If you or a family member has persistent episodes of sleep paralysis, sleep walking, or acting out of dreams, talk with your doctor.
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