What is Narcolepsy?
Narcolepsy is a chronic neurological disorder that results from the brain’s inability to regulate sleep cycles. It is a rare medical condition estimated to occur in 1 out of every 2,000 individuals. Narcolepsy can cause serious disruptions to a person’s daily activities. Most individuals with this condition have trouble falling asleep at night and experience daytime sleepiness. Many people experience uneven and interrupted sleep as well as uncontrollable, intermittent episodes of falling asleep throughout the day.
Types of Narcolepsy
There are two common types of narcolepsy:
Narcolepsy Type 1
This type shows excessive daytime sleepiness, combined with either low levels of hypocretin, characteristics of cataplexy or both. Cataplexy causes a sudden loss of muscle tone while someone is awake, such as slurred speech or even paralysis.
Narcolepsy Type 2
This type does not include cataplexy. Patients feel excessively tired during the day, but do not have muscle weakness or paralysis. The symptoms are less severe and hypocretin levels are not as irregular.
People can also develop secondary narcolepsy after an injury to the brain.
People usually begin to notice symptoms in their teenage years or early twenties. However, many people can have symptoms for years before receiving a proper diagnosis. In most cases, the condition is not diagnosed and therefore patients do not receive proper treatment.
Narcolepsy is a lifelong problem that affects everyone differently. The most common symptoms are:
Excessive Daytime Sleepiness (EDS)
Cataplexy causes muscle weakness as well as involuntary muscle control, usually emotionally triggered. Some individuals only experience one or two cataplexy attacks in a lifetime while others may experience several in one day. About 60 percent of narcoleptics experience cataplexy, but for about 10 percent, this is the first narcolepsy symptom that the patient experiences, before EDS. In severe attacks, the individual is completely paralyzed but remains fully conscious, which can lead to misdiagnosis.
People suffering from narcolepsy often experience sleep paralysis, a temporary inability to speak or move either while waking up or falling asleep. Sometimes patients have difficulty breathing. It usually lasts from a few seconds to a few minutes. These episodes can be frightening, especially for young children and teenagers. Even though the individual has no control, they remain fully conscious and may remember the paralysis. However, not everyone who experiences sleep paralysis suffers from narcolepsy.
Approximately 60 percent of narcolepsy patients may experience frightening, vivid hallucinations, either as they are falling asleep or waking up. Most often, the hallucinations are visual, but they can use other senses as well.
Rapid REM Sleep
The sleep cycle is divided into rapid eye movement (REM) sleep and non-REM sleep. People without narcolepsy enter REM sleep within 60 to 90 minutes while narcolepsy patients fall into REM sleep within 15 minutes.
People with narcolepsy may experience temporary brief sleep episodes, in which they fall asleep during daily activities, such as eating or driving, and continue doing them without realizing it.
Narcolepsy vs. Hypersomnia (IH)
Idiopathic hypersomnia is a similar condition to narcolepsy. Excessive daytime sleepiness is a major symptom of both. However, patients with IH often sleep for extremely long hours at night and have trouble waking up, while narcolepsy patients do not. Another major difference is cataplexy, which is not a characteristic of IH and almost never occurs outside of narcolepsy.
Risk Factors for Narcolepsy
Researchers do not know the exact cause of narcolepsy. They theorize that it could be caused by a deficiency in hypocretin and some believe it is associated with certain genes that control brain signals that trigger sleep and wake signals. The general consensus is that genetics, coupled with environmental triggers, affect the chemicals in the brain and cause hypocretin deficiency. Researchers have identified the following risk factors:
If the patient experiences cataplexy, they have usually lost some of the brain cells that produce hypocretin, resulting in a deficiency that research sometimes links to autoimmune disorders. For example, in narcolepsy, the immune system may mistakenly attack the cells that produce hypocretin.
Although narcolepsy is usually a sporadic disorder — meaning it doesn’t usually run in families — research has supported the possibility that it is inheritable. People who have a family member who has had narcolepsy have up to 40 percent probability of developing the disorder themselves. Approximately 10 percent of people with narcolepsy and cataplexy have a relative with the same disorder.
Other Risk Factors
Swine Flu (H1N1) Virus
Researchers have found a connection between narcolepsy and the swine flu (H1N1 FLU) virus. Some vaccinations block a receptor for hypocretin in people with a certain genetic makeup and H1N1 infection has caused symptoms similar to narcolepsy.
Heavy Alcohol Consumption
A case report suggested that narcolepsy could also be induced by chronic alcohol consumption.
Narcolepsy symptoms may not be exclusive to that disorder, so it is sometimes confused with other sleep conditions. Cataplexy is the most specific symptom that doctors use to diagnose because it appears in almost no other disorder. Doctors use a physical exam or an exhaustive evaluation of the patient’s medical history and sleep history using the following tests:
PSG records brain and muscle activity, eye movements and breathing overnight to determine if the patient falls into REM sleep early in the sleep cycle as a result of narcolepsy or of another condition.
Multiple Sleep Latency Test (MSLT)
MSLT measures how long it takes the patient to fall asleep and whether they enter the REM stage.
Epworth Sleepiness Scale (ESS)
The ESS questionnaire determines how likely the patient is to fall asleep in different circumstances.
Worn like a wristwatch, actigraphy is a monitoring system that can document sleep habits.
The lumbar puncture test collects cerebrospinal fluid from the lumbar spine to measure hypocretin levels.
Currently there is no cure for narcolepsy, but behavioral treatments and medications aim to improve symptoms so that patients can improve daytime functioning and lead a more productive life.
Modafinil – stimulates the central nervous system to reduce daytime drowsiness
Amphetamine-like stimulants – a second option to modafinil to reduce daytime sleepiness
Antidepressants – control cataplexy
Sodium oxybate – treats cataplexy and EDS
Avoid alcohol and caffeine before bed
A regular sleep schedule
The Bottom Line
Narcolepsy is a chronic neurological disorder with no known cure or definite cause. It often occurs during childhood or early adolescence, but can strike at any time. It develops when the brain is unable to regulate sleep cycles, causing excessive sleepiness during the day.
The main symptom of narcolepsy is an inability to stay awake, even when undertaking daily activities like cooking and driving. Other symptoms include cataplexy, sleep paralysis and vivid and frightening hallucinations. Though there is no cure, patients can control their symptoms with medications and lifestyle changes that aim to increase productivity.