What is Narcolepsy?
Narcolepsy is a sleep disorder characterized by excessive sleepiness during the daytime and the inability to resist falling asleep even in inappropriate situations. The condition is often accompanied by cataplexy, a sudden loss of muscle tone that strong emotions can trigger.
Symptoms of Narcolepsy
- Excessive sleepiness. Sufferers usually have trouble staying awake for extended periods, and they may fall asleep suddenly, even in the middle of a conversation or while doing work tasks. The sleepiness may cause chronic mental fogginess and trouble with concentration.
- Cataplexy. This condition causes the sufferer’s muscles to go limp suddenly. It may affect only part of the body, such as the jaw, or it may affect muscles throughout the body. Cataplexy is typically triggered by strong, often positive, emotion. The frequency of cataplexy episodes varies from person to person, and some narcolepsy sufferers don’t experience it at all.
- Hallucinations. Sufferers may experience vivid, dream-like hallucinations as they fall asleep or as they wake up. Sometimes the hallucinations may occur during what seems to be a wakeful state.
- Sleep paralysis. Sufferers may find themselves unable to move as they wake or as they fall asleep. This kind of paralysis is normal during periods of rapid-eye-movement (REM) sleep, but narcolepsy sufferers may experience it when they are otherwise awake.
- Sleep disruptions. In a typical sleep pattern, REM sleep (the sleep period during which we dream) occurs an hour or more after we first fall asleep. Narcolepsy patients often fall into REM sleep very quickly after initially falling asleep. These abnormal REM patterns are called sleep-onset REM periods (SOREMPs). Cataplexy, hallucinations, and sleep paralysis are normal characteristics of REM sleep, suggesting that the boundary between wakefulness and REM sleep is abnormally unstable in narcolepsy sufferers.
Narcolepsy sufferers may experience other sleep-related complications, including sleep apnea, insomnia, and sleepwalking.
What Causes Narcolepsy?
Narcolepsy is caused by a deficiency of a brain chemical called hypocretin. This chemical is responsible for triggering a chemical cascade in our brains that keeps us awake and alert. Narcolepsy occurs when the brain cells that produce hypocretin die.
Scientists don’t know precisely what triggers the onset of narcolepsy, but they are confident that it happens when the body’s immune system incorrectly targets hypocretin-producing brain cells. It seems that for this to happen, several factors need to come together in a particular way.
Risk factors for narcolepsy include:
- Genetics. Scientists have identified a specific gene variation associated with hypocretin production that is common among narcolepsy sufferers. However, this gene variation is also common among the general population, so it alone is not the cause of narcolepsy.
- Autoimmune reactions. Scientists have found a connection between narcolepsy and certain infections (such as strep), as well as a specific vaccine for H1N1 influenza. It’s possible that the antibodies produced in these situations, in combination with the genetic factor, could cause the immune system to target hypocretin-producing cells.
- Age. Narcolepsy most often first occurs when sufferers are young. This leads scientists to believe that there is a critical period, likely in childhood, in which the other risk factors must come together to produce narcolepsy.
In some rare cases, injury to the part of the brain that produces hypocretin can result in the form of the disorder called secondary narcolepsy.
Is Narcolepsy Hereditary?
Although the risk for narcolepsy has a genetic component, and having a family history of narcolepsy raises an individual’s risk of developing the disorder, narcolepsy is rarely inherited. The gene variation associated with narcolepsy is present in 1 out of every 4 people, but only about 1 out of every 500 people with the gene will develop narcolepsy. It appears that the gene is one risk factor for the disorder, but genes alone will not produce narcolepsy.
How is Narcolepsy Detected?
Early treatment of narcolepsy is crucial. The disorder can profoundly interfere with the sufferer’s ability to function successfully and safely in school, at work, or even in simple daily routines. The sooner that symptoms are brought under control, the better able the sufferer will be to lead a productive life.
However, early detection of the disorder can be difficult because the most common early symptom, excessive sleepiness, is not uncommon in general and can stem from many other causes. The disorder’s more distinctive signs, such as cataplexy and hallucinations, often don’t show up until later.
Often, excessive sleepiness in a young person is attributed to poor sleep habits or stress. Mental fogginess, problems with concentration, and other neurological symptoms are commonly misdiagnosed as symptoms of depression or other mental health disorders.
Therefore, it is crucial to be alert to the possibility of narcolepsy, especially when sleepiness can’t be linked to sleep habits and mental-health diagnoses don’t seem to fit.
How is Narcolepsy Diagnosed?
Initial diagnosis of narcolepsy is often made when a doctor sees signs of excessive sleepiness and other symptoms, especially cataplexy, associated with narcolepsy. To confirm the diagnosis, a general practitioner will often refer the patient to a sleep specialist. The specialist will conduct a series of exams and tests to rule out other causes of the symptoms and confirm narcolepsy.
Diagnostic steps can include:
- Sleep history questionnaires. These questionnaires will ask the patient about their sleep habits and the degree of sleepiness they feel in different situations.
- Sleep logging. The specialist will likely want to monitor the patient’s sleep for a while. Sleep patterns may either be manually recorded by the patient or recorded electronically by a device that can detect sleep and wakefulness periods. This step is aimed at finding any association between the patient’s sleep routines and their sleepiness.
- Polysomnogram. This test involves monitoring the patient’s brain activity, heart rate, muscle activity, and eye movement as they sleep. The test is conducted during an overnight stay at a medical sleep center. The test can detect abnormal patterns of REM sleep characteristic of narcolepsy, and it may detect other sleep disorders that could be causing the symptoms.
- Multiple Sleep Latency Test (MSLT). During this test, the patient is monitored during a series of short naps spaced about two hours apart. This test aims to detect any unusual periods of REM sleep that occur during the short naps.
PLEASE CONSULT A PHYSICIAN FOR MORE INFORMATION.
How is Narcolepsy Treated?
Narcolepsy is commonly treated with medications that promote wakefulness and prevent the symptoms associated with abnormal patterns of REM sleep.
Medications used to treat narcolepsy include:
- Stimulants. Modafinil and armodafinil are relatively new stimulants that help narcolepsy patients stay awake. These medications are less prone to side effects and addiction than older stimulants such as methylphenidate (Ritalin) and amphetamine, but these older medications may still be used in some cases.
- Sodium oxybate. The FDA has approved this drug to treat both sleepiness and cataplexy in patients with narcolepsy. However, it must be used with care because it can have life-threatening side effects when combined with sleep aids, narcotic pain relievers, or depressants such as alcohol.
- Antidepressants. Selective serotonin reuptake inhibitors (SSRIs) and norepinephrine reuptake inhibitors (SNRIs) such as fluoxetine and venlafaxine can help compensate for low hypocretin levels and reduce narcolepsy’s REM-related symptoms. Tricyclic antidepressants such as protriptyline, imipramine, and clomipramine may be used to treat cataplexy.
In addition to medication-based treatments, narcolepsy patients are encouraged to make changes to their lifestyle to help them achieve more healthy sleep routines. These steps can include:
- Keeping a consistent sleep schedule and avoiding intentional sleep deprivation
- Taking regular naps
- Avoiding alcohol and nicotine
- Using caffeine in moderation to promote wakefulness
- Being active and getting regular exercise
How Does Narcolepsy Progress?
Left untreated, narcolepsy can have severe consequences for the sufferer’s relationships, professional life, physical health, and safety. Potential long-term complications of narcolepsy include:
- Negative impact on school or work performance. When teachers or employers don’t understand the disorder, the sufferer may be seen as lazy or undependable.
- Social isolation. The sufferer may avoid social situations to avoid embarrassment or potentially awkward situations.
- Relationship conflicts. Cataplexy can be triggered by strong emotional reactions, leading the sufferer to disengage preemptively from relationship interactions that could be triggers.
- Weight gain. Narcolepsy sufferers are more likely than the general population to be obese.
- Safety concerns. Operating a motor vehicle or other machinery can be dangerous for a narcolepsy sufferer. Even everyday household activities such as cooking can be potentially hazardous.
How is Narcolepsy Prevented?
Because the combination of factors that cause narcolepsy is not fully understood, there is no known strategy for preventing the disorder. It is important to note that the H1N1 vaccine that has been associated with narcolepsy is a very specific type that is no longer in use (and was never used in the United States). Other vaccines have not been associated with the disorder, so avoiding vaccines will not prevent narcolepsy.
Narcolepsy Caregiver Tips
To help your loved one cope with narcolepsy, keep these tips in mind.
- Help your loved one maintain a consistent sleep schedule. Establish a routine that gives your loved one a chance to get a sufficient amount of sleep at night, and stick to the schedule. Discourage late nights or widely varying bedtimes.
- Educate others about the disorder. If you have a child with narcolepsy, make sure their teachers and school administrators understand the condition. Your child will be better able to deal with challenges at school if they have a support system there.
- Help keep everyone safe. Be aware of the risks associated with the disorder, and help your loved one avoid situations (driving, etc.) that could put them or others in danger.
Narcolepsy Brain Science
Hypocretin is a type of brain chemical called a neurotransmitter. Neurotransmitters make it possible for signals to pass from one brain cell (called a neuron) to another. Hypocretin is released when a person is awake, and its purpose is to maintain the wakeful state and prevent the person from falling into REM sleep. It does so by stimulating the production of other neurotransmitters such as norepinephrine, serotonin, and dopamine, which keep the person awake and alert.
Hypocretin is produced in a relatively small number of neurons in a part of the brain called the hypothalamus. In patients suffering from narcolepsy with cataplexy, almost all of the hypocretin-producing neurons have died. As a result, hypocretin levels are extremely low, and consequently, levels of the wakefulness-promoting neurotransmitters are also low. This helps to explain why narcolepsy sufferers are prone to falling into REM sleep or REM-like states. It also explains why antidepressant drugs, which help to elevate levels of neurotransmitters such as serotonin, are effective at treating narcolepsy symptoms.
Some people with narcolepsy don’t suffer from cataplexy, and it is not clear why. Scientists suspect that the loss of hypocretin-producing neurons isn’t complete in these cases and, thus, the symptoms are not as severe.
Title: A Web-based Observational Study of Patient-reported Outcomes in Adults With Narcolepsy
Principal investigator: JeanPierre Coaquira, MPH
Palo Alto, CA
Nexus is a collaboration between academic institutions, advocacy, and industry to answer important questions about narcolepsy. It is a web-based observational study of patient-reported outcomes in adult patients with narcolepsy, with follow-up every six months.
Title: Awareness and Self-Compassion Enhancing Narcolepsy Treatment (ASCENT)
Contact: Jason Ong, PhD
Center for Circadian and Sleep Medicine, Northwestern University
The overall goal of this research is to test the effectiveness of a mindfulness-based intervention (MBI) for improving health-related quality of life as a complementary practice to standard care for narcolepsy. This study is a feasibility trial in which 60 adults with narcolepsy will be randomized to receive either a 4-week (brief), 8-week (standard), or 12-week (extended) MBI. Each MBI will be delivered in small groups using a live videoconferencing platform and teaches mindfulness practices to help cope with narcolepsy symptoms. By developing a scalable mind-body intervention, this project can address a major research gap on improving psychosocial functioning in people with narcolepsy.
Title: Modafinil Versus Amphetamines for the Treatment of Narcolepsy Type 2 and Idiopathic Hypersomnia
Principal investigator: Lynn Marie Trotti, MD
Emory Sleep Center
Several medications can be used to treat sleepiness for diseases that cause excessive daytime sleepiness (such as narcolepsy and idiopathic hypersomnia). However, it can be difficult to decide which medication to use for a particular individual for several reasons: 1) there are very few studies that directly compare two medications to see which works best; 2) there are very few studies that include people with a disorder of sleepiness called idiopathic hypersomnia.
The researchers propose a randomized clinical trial comparing modafinil and amphetamine salts in patients with narcolepsy type 2 or idiopathic hypersomnia to address this knowledge gap. All participants will either receive modafinil or amphetamine salts — no participant will receive a placebo.
This study will evaluate which medication works better to improve sleepiness. The researchers will also see which medication is better for other symptoms, including difficulty waking up and difficulty thinking and seeing which medication causes fewer side. Finally, this study will see if any information about patients (such as age or sleep study features) predicts responding better to one medication or the other.