In severe cases, it can negatively impact social activities, school, work, and overall health and well-being. A person with narcolepsy may fall asleep at any time, such as while talking or driving. Experts believe that around 1 in 2, people have narcolepsy. It may affect ,—, people in the U.
In a typical sleep cycle, a person will first enter the early stage of sleep, then the deeper sleep stages. This is when REM sleep occurs. It takes around 60—90 minutes to reach the stage of REM sleep. For people with narcolepsy, however, REM sleep occurs within 15 minutes in the sleep cycle and intermittently during the waking hours. It is during REM sleep that vivid dreams and muscle paralysis occur. There are two main types of narcolepsy: type 1 and type 2.
Type 1 involves sleepiness and cataplexy. Tests will show that the person is almost entirely missing a neurotransmitter known as hypocretin. This may occur after an infection triggers an autoimmune condition. Secondary narcolepsy can result when trauma or a tumor results in damage to the hypothalamus. This is a part of the brain involved in sleep. The primary symptom of narcolepsy is excessive daytime sleepiness, but it may also involve cataplexy, hypnagogic hallucinations, and sleep paralysis.
It can also disrupt nighttime sleep patterns. Overall, however, a person with narcolepsy usually spends the same amount of time asleep as a person without the condition. People with narcolepsy will usually have a persistent feeling of sleepiness with a tendency to doze off at intervals throughout the day, often at inappropriate times.
Hypnogogic hallucinations are vivid, often frightening sensory hallucinations that occur while falling asleep. They may result from the blend of wakefulness and dreaming that occurs with REM sleep. Cataplexy refers to sudden muscle weakness that affects the face, neck, and knees. Sometimes, narcolepsy can be accompanied by a sudden loss of muscle tone cataplexy , which can be triggered by strong emotion. Narcolepsy that occurs with cataplexy is called type 1 narcolepsy. Narcolepsy that occurs without cataplexy is known as type 2 narcolepsy.
Narcolepsy is a chronic condition for which there's no cure. However, medications and lifestyle changes can help you manage the symptoms. Support from others — family, friends, employers, teachers — can help you cope with narcolepsy. The signs and symptoms of narcolepsy may worsen for the first few years and then continue for life. They include:. Excessive daytime sleepiness.
People with narcolepsy fall asleep without warning, anywhere, anytime. For example, you may be working or talking with friends and suddenly you nod off, sleeping for a few minutes up to a half-hour. When you awaken, you feel refreshed, but eventually you get sleepy again. You may also experience decreased alertness and focus throughout the day. Excessive daytime sleepiness usually is the first symptom to appear and is often the most troublesome, making it difficult for you to concentrate and fully function.
Sudden loss of muscle tone. This condition, called cataplexy KAT-uh-plek-see , can cause a number of physical changes, from slurred speech to complete weakness of most muscles, and may last up to a few minutes. Cataplexy is uncontrollable and is triggered by intense emotions, usually positive ones such as laughter or excitement, but sometimes fear, surprise or anger.
For example, when you laugh, your head may droop uncontrollably or your knees may suddenly buckle. Some people with narcolepsy experience only one or two episodes of cataplexy a year, while others have numerous episodes daily.
Many individuals with narcolepsy also experience uneven and interrupted sleep that can involve waking up frequently during the night. Narcolepsy can greatly affect daily activities. People may unwillingly fall asleep even if they are in the middle of an activity like driving, eating, or talking.
Other symptoms may include sudden muscle weakness while awake that makes a person go limp or unable to move cataplexy , vivid dream-like images or hallucinations, and total paralysis just before falling asleep or just after waking up sleep paralysis. In a normal sleep cycle, a person enters rapid eye movement REM sleep after about 60 to 90 minutes.
Dreams occur during REM sleep, and the brain keeps muscles limp during this sleep stage, which prevents people from acting out their dreams. People with narcolepsy frequently enter REM sleep rapidly, within 15 minutes of falling asleep. Also, the muscle weakness or dream activity of REM sleep can occur during wakefulness or be absent during sleep.
This helps explain some symptoms of narcolepsy. If left undiagnosed or untreated, narcolepsy can interfere with psychological, social, and cognitive function and development and can inhibit academic, work, and social activities.
Narcolepsy affects both males and females equally. Symptoms often start in childhood, adolescence, or young adulthood ages 7 to 25 , but can occur at any time in life.
It is estimated that anywhere from , to , people in the United States have narcolepsy. However, since this condition often goes undiagnosed, the number may be higher.
Since people with narcolepsy are often misdiagnosed with other conditions, such as psychiatric disorders or emotional problems, it can take years for someone to get the proper diagnosis. Narcolepsy is a lifelong problem, but it does not usually worsen as the person ages. Symptoms can partially improve over time, but they will never disappear completely. The most typical symptoms are excessive daytime sleepiness, cataplexy, sleep paralysis, and hallucinations.
Though all have excessive daytime sleepiness, only 10 to 25 percent of affected individuals will experience all of the other symptoms during the course of their illness. A condition known as secondary narcolepsy can result from an injury to the hypothalamus, a region deep in the brain that helps regulate sleep. In addition to experiencing the typical symptoms of narcolepsy, individuals may also have severe neurological problems and sleep for long periods more than 10 hours each night.
Narcolepsy may have several causes. Nearly all people with narcolepsy who have cataplexy have extremely low levels of the naturally occurring chemical hypocretin, which promotes wakefulness and regulates REM sleep. Hypocretin levels are usually normal in people who have narcolepsy without cataplexy. Calculating the prevalence of narcolepsy is challenging because of underdiagnosis and delays in diagnosis. Many patients are not diagnosed with narcolepsy until years after their first symptoms.
As a result, some estimates place the prevalence of narcolepsy as high as per , Narcolepsy occurs roughly equally in men and women and can affect both children and adults. It can occur at any age, but onset has been found to peak at around age 15 and again around age The symptoms of narcolepsy can have notable effects during both daytime and night time.
The most common symptoms include:. Although all people with narcolepsy have EDS, less than a quarter have all of these symptoms. In addition, the symptoms may not occur simultaneously. There is considerable overlap between narcolepsy symptoms in children and adults, but there are important differences as well.
In children, EDS is more likely to appear as restlessness or irritability , which may be interpreted as a behavior problem. At night, children with narcolepsy may sleep longer and have more active body movements during sleep. It commonly involves the face rather than the body and may be perceived as a facial tic. Cataplexy in children may not be tied to an emotional response. Over time, cataplexy symptoms in children evolve to their more traditional form.
Accidents are a pressing concern as sleep attacks, drowsiness, and cataplexy can be life-threatening when driving or in other environments where safety is critical. It is estimated that people with narcolepsy are three to four times more likely to be involved in a car accident. Narcolepsy can also interfere with school and work. Sleepiness and pauses in attention can harm performance and may be interpreted as behavioral problems, especially in children.
Many patients with narcolepsy feel stigma related to the condition that can lead to social withdrawal. Without proper support, this may contribute to mental health disorders and negatively affect school, work, and relationships. Research has started to reveal details about the underlying biology of narcolepsy, but more is known about NT1 than NT2.
Even with growing knowledge, the exact causes and risk factors for each condition are not fully understood. Narcolepsy type 1 is a disorder marked by the loss of neurons in the brain that are responsible for making hypocretin, also known as orexin , a chemical that helps regulate wakefulness and sleep. A genetically susceptible individual may experience damage to these neurons in an autoimmune fashion after an environmental trigger.
Some evidence suggests that NT1 fluctuates seasonally with a potential link to influenza flu virus. A rise in the onset of NT1 was also seen after the H1N1 epidemic and with a certain brand of vaccine used for H1N1, although this was exceedingly rare. Possible connections to other types of infections have been found as well. However, this autoimmune response inconsistently occurs and therefore is not the only cause. This gene plays a role in immune function, so this variation could cause a genetic susceptibility to NT1.
Although this explanation of NT1 is widely accepted, it is not yet definitively proven. Even though researchers know more than ever about NT1, most individual cases still occur with no clear, direct cause.
This is a small risk overall but a significant increase in risk relative to people without a family history. In rare cases, NT1 occurs because of another medical condition that causes damage to the parts of the brain containing hypocretin-producing neurons.
This may be known as secondary narcolepsy, and it can occur from brain trauma or an infection in the central nervous system. Little is known about the biology of or risk factors for NT2. Some experts believe that NT2 is simply a less pronounced loss of hypocretin-producing neurons, but people with NT2 are usually not deficient in hypocretin. In some instances, NT2 has been reported following a viral infection, but most cases do not have an established cause.
As with NT1, NT2 can arise because of other medical conditions such as head trauma, multiple sclerosis, and other diseases affecting the brain. Diagnosis of narcolepsy requires careful analysis by a doctor familiar with the disease.
Because it is rare and symptoms may be mistakenly attributed to other causes, narcolepsy can go undiagnosed for many years. The diagnostic process starts with a review of symptoms and medical history. Tests may be conducted to evaluate EDS and sleep. Polysomnography PSG , a detailed test in which sensors monitor brain and body activity, may be necessary. This kind of sleep study is done overnight in a specialized clinic.
During the MSLT, the patient is instructed to try to fall asleep at five different intervals while remaining connected to the sensors used in the PSG. Another test may be used to remove cerebrospinal fluid CSF and assess its level of hypocretin. This is done with a procedure called a spinal tap or lumbar puncture.
Low levels of hypocretin are indicative of NT1 and help distinguish it from NT2. Doctors follow standardized criteria for diagnosing sleep disorders.
Standardization helps ensure accurate diagnosis and differentiation between NT1, NT2, hypersomnias , and other conditions that cause EDS.
Other sleep disorders have similar symptoms to those found in NT2, which can make it hard to diagnose.
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