Narcolepsy facts for kids

A narcoleptic teenager waiting for cataplexy to pass

Narcolepsy is a sleep disorder. It happens when the nervous system does not work properly. People with narcolepsy tend to fall asleep during the daytime, even if they do not want to. Very often, they do not sleep well at night, and during the day they fall asleep uncontrollably. There are two different forms. The classical (more common) form is the one with muscle failure (called cataplexy). There is also a less common form without cataplexy.

Narcolepsy affects the way the nerves work. It is not a mental illness, or caused by psychological problems. It is estimated that between 25 and 50 people, per 100,000 suffer from narcolepsy. Very few cases are reported.

The first description was given in 1877. Jean-Baptiste Gélineau, a military doctor, first used the name narcolepsy in 1880.

In certain countries, people diagnosed with narcolepsy may not drive a car.

Signs and symptoms

There are two main characteristics of narcolepsy: excessive daytime sleepiness and abnormal REM sleep. Excessive daytime sleepiness occurs even after adequate night time sleep. A person with narcolepsy is likely to become drowsy or fall asleep, often at inappropriate or undesired times and places, or just be very tired throughout the day. Narcoleptics may not be able to experience the amount of restorative deep sleep that healthy people experience due to abnormal REM regulation – they are not "over-sleeping." Narcoleptics typically have higher REM sleep density than non-narcoleptics, but also experience more REM sleep without atonia. Many narcoleptics have sufficient REM sleep, but do not feel refreshed or alert throughout the day. This can feel like living their entire lives in a constant state of sleep deprivation.

Excessive sleepiness can vary in severity, and it appears most commonly during monotonous situations that do not require much interaction. Daytime naps may occur with little warning and may be physically irresistible. These naps can occur several times a day. They are typically refreshing, but only for a few hours or less. Vivid dreams may be experienced on a regular basis, even during very brief naps. Drowsiness may persist for prolonged periods or remain constant. In addition, night-time sleep may be fragmented, with frequent awakenings. A second prominent symptom of narcolepsy is abnormal REM sleep. Narcoleptics are unique in that they enter into the REM phase of sleep in the beginnings of sleep, even when sleeping during the day.

The classic symptoms of the disorder are cataplexy, sleep paralysis, hypnagogic hallucinations, and excessive daytime sleepiness. Other symptoms may include automatic behaviors and night-time wakefulness. These symptoms may not occur in all people with narcolepsy.

• An episodic loss of muscle function, known as cataplexy, ranging from slight weakness such as limpness at the neck or knees, sagging facial muscles, weakness at the knees often referred to as "knee buckling", or inability to speak clearly, to a complete body collapse. Episodes may be triggered by sudden emotional reactions such as laughter, anger, surprise, or fear. The person remains conscious throughout the episode. In some cases, cataplexy may resemble epileptic seizures. Usually speech is slurred and vision is impaired (double vision, inability to focus), but hearing and awareness remain normal. Cataplexy also has a severe emotional impact on narcoleptics, as it can cause extreme anxiety, fear, and avoidance of people or situations that might elicit an attack. Cataplexy is generally considered to be unique to narcolepsy and is analogous to sleep paralysis in that the usually protective paralysis mechanism occurring during sleep is inappropriately activated. The opposite of this situation (failure to activate this protective paralysis) occurs in rapid eye movement behavior disorder.
• Periods of wakefulness at night
• The temporary inability to talk or move when waking (or less often, when falling asleep), known as sleep paralysis. It may last a few seconds to minutes. This is often frightening but is not dangerous.
• Vivid, often frightening, dreamlike experiences that occur while dozing or falling asleep, known as hypnagogic hallucinations. Hypnopompic hallucinations refer to the same sensations while awakening from sleep. These hallucinations may manifest in the form of visual or auditory sensations.

In most cases, the first symptom of narcolepsy to appear is excessive and overwhelming daytime sleepiness. The other symptoms may begin alone or in combination months or years after the onset of the daytime naps. There are wide variations in the development, severity, and order of appearance of cataplexy, sleep paralysis, and hypnagogic hallucinations in individuals. Only about 20 to 25 percent of people with narcolepsy experience all four symptoms. The excessive daytime sleepiness generally persists throughout life, but sleep paralysis and hypnagogic hallucinations may not.

Narcoleptics can gain excess weight; children can gain 20 to 40 pounds (9.1 to 18.1 kg) when they first develop narcolepsy; in adults the body-mass index is about 15% above average.

Causes

The exact cause of narcolepsy is unknown, and it may be caused by several distinct factors. The mechanism involves the loss of orexin-releasing neurons within the lateral hypothalamus (about 70,000 neurons).

Some researches indicated that people with type 1 narcolepsy (narcolepsy with cataplexy) have a lower level of orexin (hypocretin), which is a chemical contributing to the regulation of wakefulness and REM sleep. It also acts as a neurotransmitter to enable nerve cells to communicate.

In up to 10% of cases there is a family history of the disorder. Family history is more common in narcolepsy with cataplexy. There is a strong link with certain genetic variants, which may make T-cells susceptible to react to the orexin-releasing neurons (autoimmunity) after being stimulated by infection with H1N1 influenza. In addition to genetic factors, low levels of orexin peptides have been correlated with a history of infection, diet, contact with toxins such as pesticides, and brain injuries due to head trauma, brain tumors or strokes.

Treatments

There are certain drugs that can treat the effects of narcolepsy. They can not treat the cause, since it is unknown. In general those drugs are special kinds of stimulants. General stimulants, like coffee, usually do not help. Some strategies for treatment do not rely on drugs:

• Adapting the behaviour to avoid situations that trigger daytime sleep; this is generally known as coping. It also involves changing the daytime rhythm to accommodate the sleeping phases.
• Sleep hygiene

See also

In Spanish: Narcolepsia para niños