Narcolepsy

What is narcolepsy

Narcolepsy is a severe sleep disorder that can interfere with normal lifestyle. It is a condition in which the brain's ability to maintain alertness does not function normally, and the sufferer involuntarily falls asleep at inappropriate times.

People with narcolepsy are afflicted with multiple and sudden 'sleep attacks' during the day, sometimes even falling asleep in the middle of a conversation. Although these attacks usually only last about 10-15 minutes, they may continue for several hours or more if the person is comfortably positioned when the attack occurs.

The type of sleep that occurs is known as REM (rapid eye movement) sleep. During normal sleep cycles, REM sleep is preceded by a non-REM phase of sleep lasting up to an hour. But with people suffering from narcolepsy, the non-REM phase is skipped, and the person falls immediately into REM sleep.

Cataplexy: This can range from a brief weak­ness in the legs to the total paralysis of all voluntary muscles while the person is fully conscious. Cataplexy is usually precipitated by a sudden emotional outburst, such as laughing, crying, anger, fear, or other excitement.

Cataplexy itself seems to be an exaggeration in the experience of the person who, for example, becomes 'weak with laughter'.

Attacks are usually brief but frightening.

Narcolepsy with cataplexy has a known cause, related to a loss of cells in the brain that secrete hypocretin (also called orexin). Hypocretin is a chemical in the brain that is important for regulating wakefulness.

With narcolepsy, the boundaries between sleep and wakefulness are blurred, causing a person to feel very sleepy and fatigued during the day, have vivid dream-like hallucinations and paralysis while falling asleep or waking up, and experience disrupted nighttime sleep. 

Sleep paralysis: This refers to episodes occurring either just before falling asleep or upon awakening, when the individual sud­denly finds it impossible to move for a few seconds.

The only muscles capable of voluntary movement during these episodes are those controlling the eyes. Sleep paralysis is similar to the inhibition of muscle activity that normally occurs during the REM stage of sleep.

Hypnagogic hallucinations: These are vivid auditory or visual illusions. In normal people they may occur just at the wake-sleep point, or at sleep-wake, when they are called hypnopompic.

In the narcoleptic they occur during consciousness.

What causes narcolepsy

While the cause of narco­lepsy is unknown, it may sometimes occur after a brain infection or head injury. However, the disor­der usually develops in adolescents or young adults without any identi­fiable brain abnormality.

It is four times more common in men than in women, and sometimes appears to run in families.

Narcolepsy is not a progressive disease, and, although it persists for life, it is not thought to have any impact on life expectancy.

The nature of narcolepsy does not usually change over the course of a life­time. Sleep attacks may occur only a few times a day, or so often as to inter­fere with getting anything done at all.

Although sufferers fall asleep rapidly during the day, they can easily be roused. However, no matter how long the sleep attack, the person does not feel refreshed upon awakening.

Narcoleptics may walk around in a continual state of drowsiness and may rarely feel fully alert. In addition, night-time sleep may be unsatisfactory and disrupted by vivid dreams.

How is narcolepsy diagnosed and treated

Although the diagnosis may seem obvious by the individual's description of the disorder's characteris­tic symptoms, it may be confirmed by referral to a sleep laboratory for observation, or by an investigative procedure known as electroenceph­alography [EEG], which measures the brain's electrical impulses.

In a case of narcolepsy, the EEG result will show the characteristic electrical pattern associated with REM sleep intruding into periods of wakefulness.

Treatment of narcolepsy can be difficult. In most cases, in addition to recommending scheduled nap times during the day, doctors will prescribe stimulant drugs, such as amphetamines, to assist in

maintaining wakefulness.

Certain antidepressants are also useful in the treatment of narcolepsy and have been shown to help reduce the incidence of cataplexy.

When should I see my doctor

Repeated abnormal sleep phenomena during the day should prompt a visit to the doctor.

What will the doctor do

After taking a full medical history, your doctor may refer you to hospital for further investigation (EEG) and treatment.

What can I do myself

Is narcolepsy dangerous

Normally narcolepsy is not dangerous, but it can be extremely inconvenient and embarrassing for the sufferer. However, if they have a sleep attack while driving or operating machinery, narcoleptics risk causing themselves, and others, serious injury.

Standard Therapies

Treatment

The treatment of narcolepsy is directed toward the specific symptoms that are present in each individual. Various medications may help to alleviate certain symptoms associated with narcolepsy.

For individuals who experience excessive daytime sleepiness and sleep attacks, therapy may include administration of certain stimulants, such as modafinil (Provigil). Modafinil was approved by the Food and Drug and Administration (FDA) for the treatment of excessive daytime sleepiness in narcolepsy in 1999. Modafinil is now the most widely prescribed drug for excessive daytime sleepiness.

The drug’s mechanism of action appears to differ from that of other stimulants and does not appear to affect alertness or memory. In addition, evidence suggests that modafinil therapy is not associated with dependency or symptoms of withdrawal and therefore may be an effective alternative to other treatments for excessive daytime sleepiness. Modafinil is generally associated with fewer side effects than previous drugs used to treat this condition.

Previous drugs that have been used to treat excessive daytime sleepiness in narcolepsy include methylphenidate (Ritalin, Methylin), methamphetamine, or dextroamphetamine. These drugs stimulate the central nervous system and are still used when modafinil is unsuccessful.

Because such medications may be associated with certain side effects, including nervousness, insomnia, or irritability, careful monitoring by physicians is required to ensure appropriate dosage adjustments and effectiveness of such therapy. In addition, close monitoring and long-term follow-up by physicians may be required if therapy is withdrawn.

Additional stimulants that have been used to treat excessive daytime sleepiness and narcolepsy include manzindol, selegiline, and pemoline.

A variety of drugs have been used to treat cataplexy. The orphan drug Xyrem, manufactured by Jazz Pharmaceuticals, has been approved by the FDA to treat cataplexy, the sudden loss of muscular control and weakness that is associated with narcolepsy.

Xyrem has also been effective in improving nighttime sleep in individuals with narcolepsy. Some individuals with narcolepsy treated with high doses of the drug showed improved of daytime sleepiness. However, Xyrem is potentially associated with serious side effects. The generic name for Xyrem is sodium oxybate and it is also known as gamma hydroxybutyrate or GHB.

Individuals with cataplexy, sleep paralysis and/or hypnagogic hallucinations may be treated with certain antidepressants. Specifically, doctors often prescribe selective serotonin reuptake inhibitors, which suppress rapid eye movement sleep, to help alleviate these symptoms.

These drugs include for example, fluoxetine (Prozac, Serafem, others), sertraline (Zoloft), atomoxetine (Strattera) and venlafaxine (Effexor). The most common side effects are decreased sexual desire and delayed orgasm.

Other side effects can include digestive problems, restlessness, headache and insomnia. Older tricyclic antidepressants such as imipramine, desimipramine, protriptyline, and clomipramine may also be effective in reducing cataplexy, sleep paralysis and/or hallucinations, but many people are bothered by side effects, including dry mouth and constipation.

Close monitoring by a physician is necessary for those taking antidepressant medications and is also required if such therapy is withdrawn.