What Causes Narcolepsy?
Although the exact cause is presently not fully understood, narcolepsy appears to be a disorder of the part of the brain that controls sleep and wakefulness. As a result, sleep or parts of sleep intrude into wakefulness. The symptom most easily understood is the sleepiness, which is just the brain being unable to control when the individual falls asleep. Other symptoms, such as cataplexy ( loss of muscle tone at times of strong emotion) and sleep paralysis are similar to the loss of muscle tone of dreaming that accompanies a normal part of sleep called REM. In people with narcolepsy, these events (the lack of muscle tone or the dream experiences) occur at inappropriate times while they are awake. Narcolepsy is not caused by psychiatric or psychological problems. Sometimes narcolepsy runs in families, but many people with narcolepsy do not have relatives who are affected. Recent studies have found low levels of a brain chemical called hypocretin in people with narcolepsy. Some researchers have suggested that a problem with the gene responsible for making hypocretin, combined with other factors in a person’s life, may cause the disorder.
What Are The Symptoms Of Narcolepsy?
The four most common symptoms of narcolepsy are: 1) excessive daytime sleepiness, 2) cataplexy, 3) sleep paralysis, and 4) hypnagogic hallucinations. In most cases, excessive daytime sleepiness is the most bothersome symptom. The symptoms of narcolepsy can appear all at once or can develop gradually over many years, and in up to one-third of patients, sleepiness is the only symptom.
Excessive Daytime Sleepiness
Daytime sleepiness is present in all narcoleptics and is usually the first symptom that appears. People with narcolepsy report feeling continually tired or sleepy all the time. They tend to fall asleep not only in situations in which many people normally feel sleepy (after meals or during a dull lecture), but also when most people would remain awake (while having a conversation, writing a letter, or watching a movie). These “naps” tend to be short and may be refreshing, at least for a short period of time. People with narcolepsy may become drowsy or feel foggy at very unusual times, even in dangerous situations, such as while driving.
Attacks of cataplexy – sudden, brief losses of muscle strength – are sometimes the first symptom of narcolepsy, but more often develop months or years after the onset of sleepiness. Cataplexy can be mild – such as a brief feeling of weakness in the knees – or it may cause a complete physical collapse, resulting in a fall. A person having such an attack is fully awake and knows what is happening. Cataplexy is usually triggered by strong emotion, such as laughter, anger, surprise, or fear. In some individuals, simply remembering or anticipating an emotional or anxiety-producing situation can produce attacks.
Sleep Paralysis is also a brief loss of muscle strength, but it occurs when a person is falling asleep or waking up. The person may be somewhat aware of his or her surroundings, but is unable to move or speak. Sleep paralysis can be frightening but is not dangerous, since the muscles that maintain life (the main breathing muscles and the heart) are not affected.
Hypnagogic hallucinations are vivid dreams that occur when a person is drowsy, or just entering sleep. The hallucinations may involve disturbing images or sounds, such as of strange animals or prowlers. These hallucinations may be frightening because the person is partly awake but has no control over the events. The dreams can also be upsetting if they are mistaken for hallucinations caused by mental illness.
When To See A Healthcare Professional
If you experience any of the above symptoms of narcolepsy and especially if you find them affecting your ability to drive, hold a job, stay in school, and perform normal daily activities, or if the symptoms are interfering with your social activities and personal relationships, it is important for you to see your healthcare professional.
How is Narcolepsy Diagnosed
The first step in diagnosing this disorder would be an evaluation by your healthcare professional to make sure that some other medical illness is not the cause. The next step is usually a visit to a sleep specialist.
At a sleep disorders center, the specialist would thoroughly review your medical history and perform a complete physical examination. If the specialist suspects narcolepsy, you will usually be asked to undergo testing at the sleep center. Two tests, a polysomnogram and a multiple sleep latency test (MSLT), are commonly performed to confirm the diagnosis of narcolepsy and determine its severity.
During a polysomnogram, you would spend the night at the sleep center in a comfortable private room. Small electrodes placed on your skin record brain waves, muscle activity, heart rate, and eye movements, while other devices measure breathing. The procedure is painless and does not involve needles. This test is needed to determine whether you have other disorders that may be contributing to your symptoms.
An MSLT is conducted the following day. With the electrodes still in place, you will be asked to take four of five 20-minute naps at two-hour intervals. The MSLT monitors how quickly you fall asleep and also your sleep pattern, since people with narcolepsy frequently have REM (dreaming) sleep even during a brief nap. Consequently, these two tests – together with your symptoms and sometimes a blood test called HLA typing – help the sleep specialist determine whether symptoms are caused by narcolepsy or by another disorder that shares some of its features.
How Is Narcolepsy Treated?
Although narcolepsy cannot be cured, its symptoms can usually be controlled or improved so that sufferers experience symptoms less frequently and lead fairly normal lives. If you are diagnosed with narcolepsy, your treatment plan would likely have several parts: medication, behavior treatment, and management of your environment. Also, it is quite common to have other sleep disorders such as obstructive sleep apnea, periodic limb movements during sleep, and REM sleep behavior disorder, all of which may worsen the quality of sleep , and for which specific treatments are available.
Over-the-counter medications containing caffeine usually do not work well for narcolepsy. However, prescription medications are available and can be effective in controlling excessive daytime sleepiness, cataplexy, hallucinations, and sleep disruptions. These medications include stimulants like methylphenidate and amphetamines or wakefulness-promoting agents like modafinil to control the sleepiness, and other medications that suppress cataplexy, sleep paralysis, and hypnagogic hallucinations. Sodium oxybate is a relatively new product that is quite powerful, and can be used to control excessive sleepiness and cataplexy. You and your healthcare professional must work together to find the best balance between control of the symptoms and unwanted side effects of a drug.
Treating your narcolepsy would probably require not only medication, but also adjustments in your lifestyle. Following these suggestions may significantly improve your feeling of well being:
- Follow a regular sleep/wake schedule. Go to bed and get up approximately the same time each day. People with narcolepsy generally should not work night shifts or changing shifts, or inordinately long work hours.
- Regular short naps may be helpful since it is generally harder for people with narcolepsy to fall asleep within an hour or two after a nap.
- Be cautious during activities that can be dangerous if you fall asleep or have an episode of cataplexy, such as driving or cooking; try to plan your schedule so that you will be alert at these times.
- Carefully follow your healthcare professional’s instructions regarding medications. Immediately inform him or her of any changes or problems with your medications.
- Be sure that your family, friends and employer/teachers are aware of your condition and understand the associated symptoms, and the medications you take.