Understanding Narcolepsy: Symptoms, Diagnosis, and Treatment
Narcolepsy is a chronic neurological disorder that affects the brain’s ability to regulate the sleep-wake cycle. People with narcolepsy experience excessive daytime sleepiness, sudden attacks of sleep, and abnormal rapid eye movement (REM) sleep. Narcolepsy can have a significant impact on the quality of life, affecting the physical, mental, and social aspects of daily living.
In this article, you will learn about:
- What is Narcolepsy?
- Clinical Symptoms of Narcolepsy
- How is Narcolepsy Diagnosed?
- Polysomnography (PSG)
- Multiple Sleep Latency Test (MSLT)
- Genetics Related to Narcolepsy
- Treatment of Narcolepsy
- Patient and Family Education
- Sleep Hygiene
- Napping
- Safety Issues
- Medications
- Frequently Asked Questions
- Can narcolepsy be fatal?
- Is narcolepsy a rare disease?
- Reference
Table of Contents
- What is Narcolepsy?
- Clinical Symptoms of Narcolepsy
- How is Narcolepsy Diagnosed?
- Genetics Related to Narcolepsy
- Treatment of Narcolepsy
- Frequently Asked Questions
- Reference
What is Narcolepsy?
Narcolepsy is a rare sleep disorder characterized by severe symptoms of excessive sleepiness. It involves a disruption in the central nervous system’s control of sleep and wakefulness, leading to sudden episodes of deep sleep even during wakefulness. The exact pathophysiology of narcolepsy is still not fully understood, but recent research suggests that it is caused by a loss of orexin (also known as hypocretin), a neurotransmitter that regulates arousal, wakefulness, and appetite.
People with narcolepsy find it challenging to stay awake, often experiencing intense sleepiness and sudden sleep onset, even at inappropriate times or during emotionally arousing situations. It is generally believed that narcolepsy episodes are triggered by the sudden occurrence of rapid eye movement (REM) during wakefulness. REM sleep is the stage of sleep where most vivid dreams occur, and it is normally suppressed during the day. However, in people with narcolepsy, REM sleep can intrude into wakefulness, causing a loss of muscle tone, hallucinations, and sleep paralysis. Narcolepsy is a cyclic and uncontrollable short-term sleep attack within a confined time frame, with the main cause being a malfunction in the central nervous system’s control of sleep and wakefulness. The primary symptoms occur when the brain and body suddenly exhibit physiological responses associated with dreaming (clinically known as rapid eye movement).
Clinical Symptoms of Narcolepsy
The main symptoms of narcolepsy are:
- Daytime Sleepiness: Falling asleep unexpectedly, especially during monotonous activities or solitary work. These sudden sleep episodes become more frequent and may occur at inappropriate or dangerous times, such as while driving, working, or studying. The duration of these episodes can range from a few seconds to several minutes, and they are usually refreshing but not restorative. People with narcolepsy may also have difficulty waking up in the morning and feel groggy throughout the day.
- Cataplexy: Sudden loss of muscle stability and strength, leading to a potential fall. In individuals with normal sleep and wakefulness, the loss of muscle tone occurs during rapid eye movement (REM) sleep. However, in people with narcolepsy, cataplexy can be triggered by strong emotions, such as laughter, anger, surprise, or fear. Cataplexy can affect any part of the body, from the face to the legs, and can range from mild (such as drooping eyelids or slurred speech) to severe (such as complete collapse). Cataplexy usually lasts from a few seconds to a few minutes, and the person remains conscious and aware of their surroundings.
- Sleep Paralysis: Inability to move limbs upon waking up or before falling asleep due to the loss of muscle tone. Sleep paralysis can be frightening and may be accompanied by hallucinations. It usually lasts from a few seconds to a few minutes, and the person can break out of it by trying to move a finger or toe, or by someone else touching them.
- Hypnagogic Hallucinations: Before sleep, a mixture of dreams and the real world leads to visual, auditory, and tactile hallucinations. These hallucinations can be realistic and vivid, and may involve people, animals, objects, or sounds. They can be pleasant or terrifying, and may cause confusion and distress. Hypnagogic hallucinations can also occur during sleep paralysis or cataplexy.
Not all people with narcolepsy experience all of these symptoms, and the severity and frequency of each symptom can vary from person to person. Some people may also have other symptoms, such as:
- Automatic Behavior: Performing routine tasks without conscious awareness or memory, such as writing, driving, or eating. This can occur during a brief sleep episode or a state of reduced alertness.
- Memory Problems: Having difficulty remembering recent events, conversations, or instructions, especially if they occurred during a sleep episode or a state of reduced alertness.
- Fragmented Nighttime Sleep: Having trouble falling asleep or staying asleep at night, due to insomnia, restless legs syndrome, periodic limb movements, or sleep apnea. This can result in poor sleep quality and increased daytime sleepiness.
How is Narcolepsy Diagnosed?
Narcolepsy is a complex disorder that requires a comprehensive evaluation to reach an accurate diagnosis. The diagnosis of narcolepsy is based on clinical criteria, objective tests, and the exclusion of other causes of excessive daytime sleepiness. The main tests used to diagnose narcolepsy are overnight polysomnography (PSG) and multiple sleep latency test (MSLT), which are usually performed by a sleep specialist in a sleep laboratory.
Polysomnography (PSG)
Polysomnography (PSG) is a test that records various physiological signals during a night’s sleep, such as brain waves, eye movements, muscle activity, heart rate, breathing, and blood oxygen levels. PSG can detect abnormalities in sleep stages, sleep continuity, and sleep-related breathing disorders. PSG can also help to rule out other conditions that may cause or worsen daytime sleepiness, such as insomnia, restless legs syndrome, or sleep apnea.
Multiple Sleep Latency Test (MSLT)
Multiple Sleep Latency Test (MSLT) is a test that measures how quickly and how often a person falls asleep during the day. MSLT consists of four or five nap opportunities, each lasting 20 minutes, spaced two hours apart. During each nap, electrodes are attached to the skin to record brain waves and eye movements. MSLT can assess the degree of daytime sleepiness and the presence of rapid eye movement (REM) sleep, which is the stage of sleep associated with dreaming and muscle paralysis. People with narcolepsy tend to fall asleep faster and enter REM sleep sooner than normal during MSLT.
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Genetics Related to Narcolepsy
Narcolepsy is a multifactorial disorder that involves genetic and environmental factors. The genetic basis of narcolepsy is not fully understood, but several genes have been implicated in its pathogenesis. The most important genetic factor is the human leukocyte antigen (HLA) system, which is involved in the immune response and self-recognition. About 90% of people with narcolepsy have a specific HLA type, called HLA-DQB1*06:02, compared to 25% of the general population. However, this HLA type is not sufficient to cause narcolepsy, as only a small fraction of people with this HLA type develop narcolepsy. Other genes that may influence the risk of narcolepsy include those that encode for hypocretin (orexin), a neuropeptide that regulates wakefulness and appetite, and its receptors, as well as genes that affect the immune system, the circadian rhythm, and the dopamine system.
Patient and Family Education
Learning about narcolepsy and its impact on daily functioning is essential for patients and their families. Education can help them cope with the emotional and practical challenges, such as stigma, discrimination, occupational limitations, and safety risks. Education can also help them find support from other people with narcolepsy, health care professionals, and advocacy groups.
Sleep Hygiene
Sleep hygiene refers to the habits and practices that promote good sleep quality and daytime alertness. For people with narcolepsy, sleep hygiene includes:
- Following a regular sleep/wake schedule and avoiding significant changes on weekends or holidays.
- Maintaining a comfortable and quiet sleeping environment, free of distractions and interruptions.
- Avoiding caffeine, alcohol, nicotine, and heavy meals close to bedtime.
- Engaging in relaxing activities before bed, such as reading, listening to music, or meditation.
- Avoiding naps during the late afternoon or evening, as they may interfere with nighttime sleep.
Napping
Napping is a useful strategy to manage excessive daytime sleepiness and improve alertness and performance. However, napping should be planned and controlled, rather than spontaneous and uncontrollable. Some tips for effective napping are:
- Schedule naps at regular times during the day, preferably in the early afternoon.
- Limit naps to 15-20 minutes, as longer naps may cause grogginess and difficulty falling asleep at night.
- Find a safe and comfortable place to nap, such as a couch, a recliner, or a bed.
- Use an alarm clock or a timer to wake up from the nap.
- Avoid napping too close to bedtime, as it may delay sleep onset and reduce sleep quality.
Safety Issues
People with narcolepsy may face safety risks due to their symptoms, especially excessive daytime sleepiness and cataplexy. These risks include falling asleep while driving, operating machinery, cooking, or performing other tasks that require attention and coordination. To prevent accidents and injuries, people with narcolepsy should:
- Consult with their health care provider about their ability to drive and the potential effects of medications on driving performance.
- Follow the laws and regulations regarding driving with narcolepsy in their state or country.
- Avoid driving when feeling sleepy, especially during long or monotonous trips.
- Take frequent breaks and naps during driving, and have a companion who can take over the driving if needed.
- Use devices or apps that can alert them if they show signs of drowsiness or inattention while driving.
- Inform their employer, co-workers, family, and friends about their condition and the possible triggers and manifestations of cataplexy.
- Develop coping strategies to deal with cataplexy episodes, such as holding onto something, sitting down, or lying down.
- Wear a medical alert bracelet or carry a card that identifies them as having narcolepsy and provides emergency contact information.
Medications
Medications are often prescribed to treat the symptoms of narcolepsy, such as excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. The choice of medication depends on the type and severity of symptoms, the patient’s medical history, and the potential benefits and risks. Some of the common medications for narcolepsy are:
| Medication | Class | Effect | Side Effects |
|---|---|---|---|
| Modafinil (Provigil) and Armodafinil (Nuvigil) | Stimulants | Improve alertness and reduce daytime sleepiness | Headache, nausea, insomnia, anxiety, hypertension |
| Methylphenidate (Ritalin) and Amphetamine (Adderall) | Stimulants | Improve alertness and reduce daytime sleepiness | Headache, nausea, insomnia, anxiety, hypertension, addiction, tolerance |
| Sodium oxybate (Xyrem) | GABA agonist | Reduce cataplexy and improve nighttime sleep quality | Nausea, dizziness, headache, confusion, depression, respiratory depression, abuse potential |
| Antidepressants (e.g., Venlafaxine, Fluoxetine, Clomipramine) | SNRI, SSRI, TCA | Reduce cataplexy, hypnagogic hallucinations, and sleep paralysis | Nausea, dry mouth, weight gain, sexual dysfunction, cardiac arrhythmia |
| Pitolisant (Wakix) | Histamine H3 receptor antagonist | Improve alertness and reduce daytime sleepiness | Headache, nausea, insomnia, anxiety |
| Solriamfetol (Sunosi) | Dopamine and norepinephrine reuptake inhibitor | Improve alertness and reduce daytime sleepiness | Headache, nausea, insomnia, anxiety, hypertension |
Medications for narcolepsy should be taken under the guidance of a health care provider, who can monitor the response and adjust the dosage and frequency as needed. Medications should not be stopped abruptly, as this may cause withdrawal symptoms or rebound effects. Medications should also be used in combination with behavioral and lifestyle interventions, as they are not a substitute for good sleep hygiene and napping.
Frequently Asked Questions
Can narcolepsy be fatal?
Narcolepsy is not a life-threatening condition in itself, but it can increase the risk of accidents and injuries due to excessive daytime sleepiness and cataplexy. People with narcolepsy may also have higher rates of depression, anxiety, and other mental health problems that can affect their quality of life and well-being. Additionally, some studies have suggested that narcolepsy may be associated with an increased risk of cardiovascular disease, metabolic syndrome, and cancer . However, these findings are not conclusive and need further investigation. Therefore, it is important for people with narcolepsy to seek medical attention, follow their treatment plan, and adopt healthy lifestyle habits to reduce the potential complications of narcolepsy.
Is narcolepsy a rare disease?
Narcolepsy is considered a rare disease, as it affects less than 200,000 people in the United States and less than 5 per 10,000 people worldwide. However, the exact prevalence of narcolepsy is unknown, as many cases may be undiagnosed or misdiagnosed due to the lack of awareness and the complexity of the symptoms. Some studies have estimated that narcolepsy may affect up to 1 in 2,000 people in some regions, such as Europe and Japan . Narcolepsy can affect anyone, regardless of age, gender, ethnicity, or family history, although it usually begins in adolescence or young adulthood. Narcolepsy is a chronic condition that lasts for a lifetime, but it can be managed with proper treatment and support.
Reference
- Scammell, T. E. (2015). Narcolepsy. New England Journal of Medicine, 373(27), 2654-2662.
- Jennum, P., Ibsen, R., Petersen, E. R., Knudsen, S., & Kjellberg, J. (2012). Health, social, and economic consequences of narcolepsy: a controlled national study evaluating the societal effect on patients and their partners. Sleep medicine, 13(8), 1086-1093.
- National Organization for Rare Disorders. (2018). Narcolepsy. Retrieved from
- Dauvilliers, Y., Arnulf, I., & Mignot, E. (2007). Narcolepsy with cataplexy. The Lancet, 369(9560), 499-511.
- Ohayon, M. M., Priest, R. G., Zulley, J., Smirne, S., & Paiva, T. (2002). Prevalence of narcolepsy symptomatology and diagnosis in the European general population. Neurology, 58(12), 1826-1833.
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