Narcolepsy: An Overview


Click here for 'Causes of Narcolepsy.'

There has been significant polemics in the beginning of 21st century over the incidence of Narcolepsy. It is one of the many disorders that have been particularly difficult to diagnose. Some patients went on for ten years before being correctly diagnosed.  According to National Institute of Neurological Disorders and Stroke or NINDS (2011), one of every 2000 Americans has Narcolepsy.

It is also the second leading cause of excessive daytime sleepiness, next only to sleep apnea. Studies on the epidemiology of narcolepsy show an incidence of 0.2 to 1.6 per thousand in European countries, Japan and the United States, a frequency at least as large as that of Multiple Sclerosis (Honda, 1979; Lavie, 1987).

There are about 135,000 or recorded cases in the United States. Yet, there are very limited researches or available information that could help in identifying the causes and possible cure.

One of the greatest leaps in the study of Narcolepsy is the discovery of canine narcolepsy gene. This led to the reevaluation of the physiological causes and environmental causes of human narcolepsy. This essay will reevaluate what discoveries have been made to identify the causes of Narcolepsy and draw out recommendations on what future studies must concentrate on in order to prevent or cure the disorder.

Symptoms of Narcolepsy

There are four symptoms of Narcolepsy.

Sleep Attacks – people can abruptly fall a sleep with no warning. They can be in the middle of their funny story and then just fell asleep. It happens sporadically and it happens several times a day. The person with the disease often don’t know that they are about to sleep or they just fell asleep. They could feel refreshed but still suddenly sleep after just a couple of minutes.

For the longest time, researchers thought that ordinary sleep and narcoleptic sleep are the same, later studies have revealed that a Normal sleep is a cyclical process that alternates between periods of rapid-eye-movement (REM) and non­rapid-eye-movement (NREM) sleep. When one is under the NREM part, the whole body’s physical process slow down including pulse, metabolism, heartbeat,  blood pressure, and brain wave activity. When the body goes into REM cycle begins, the brain becomes more active even when the whole body is still asleep. This was recorded using electroencephalograph (EEG). This is when people start dreaming.  For healthy people, sleep actually begins in the NREM phase and it takes them an hour to go into the REM stage. After an hour or less, the body enters NREM and then REM, and so on (Guilleminault, 1987).

During a narcoleptic sleep, the body doesn’t go into NREM. It goes straight into REM.

Cataplexy – is a type of paralysis caused by high emotions such as anger, excitement or sadness. The person doesn’t exactly fall asleep but loses the ability to move. Some people find that only the limbs are affected but others actually lose the ability to movie their entire body. This stage can carry on for a couple of minutes (Gelb et al, 1994).

Sleep paralysis – is when a person finds it impossible to move just as he or she is waking up. This usually last less than a minute (Hishikawa et al, 1995).

Hypnagogic (sleep-related) hallucinations – this happens before going to sleep or just as when a person is waking up. As the name indicates, the person experiences hallucinations including hearing sounds that were not even there. These episodes are vivid and it is not surprising for people to think the hallucinations are real (Dement, 1976).

How Common is Narcolepsy ?

As mentioned above, NINDS estimates that one in every 2,000 Americans has Narcolepsy but there are even more experts who believe that it is underdiagnosed because people will most likely have only one of the four symptoms especially among children. Hallucinations, for example, are often brushed off and may be believed as the development of the child’s creativity. It is only when other symptoms appear will there be a consideration that it could Narcolepsy.

The other difficulty is the lack of manifestations that may be visitble during routine physical examination. Most often, a doctor will only basis his diagnosis from reports or or historical records. A formal diagnosis will only be made after actual tests. One of the tests conducted is the Epworth Sleepiness Scale (ESS). The test aims to determine how likely people are to fall asleep during eight different events. Each question has a corresponding rating. When the total goes over 24, a laboratory test must be conducted (Broughton, 1976).

MRI or CT scans are conducted only to scan for possible tumor but are not necessary in determining whether a person has Narcolepsy or not.

What must be conducted is a test called overnight polysomnogram. This is when a person is monitored by attaching electrocardiography on the head to trace brain wave activity, respiratory parameters and a video camera recording (Hishikawa and Shimizu 1995).

A multiple sleep latency test will also be conducted to determine how fast a person goes into REM. When a person goes into REM within five minutes, that’s a strong sign of Narcolepsy. Another test that must be performed is a blood test to examine the genes. Recent studies have allowed a better understanding on how Narcoplepsy may also be genetic.

However, even when there are positive results, it doesn’t conclude that a person has Narcolepsy. It only suggests that there is a possibility of a person is Narcoleptic. In the first half of last decade, a new test involves taking a sample of a person’s cerebrospinal fluid through the spinal tap. This fluid is tested for hypocretin-1. When there is none found, the patient is conclusively narcoleptic (Epstein & Mardon, 2007).

Aside from possible bumps that may be experienced with a person falls, there is no other danger involve in narcolepsy. It does not affect a person’s life expectancy nor is it develop any neurological symptom. If there is anything that will be affected, it will most likely be a person’s social life and other social activities. A football coach will not go with a Narcoleptic for his quarterback.

Click here for 'Causes of Narcolepsy.'