Narcolepsy

Narcolepsy is an uncommon condition in which the sleep-wake regulators in the brain do not function correctly. Because of this, sufferers are excessively sleepy by day and fall asleep at inappropriate times. So-called 'sleep attacks' may result from an overwhelming sense of daytime sleepiness.

People who suffer from narcolepsy often also experience episodes of cataplexy, in which there is a dramatic reduction in muscle tone in association with emotional triggers such as laughing, joking, surprise, fear or anger. Depending on the severity, this can cause minor effects such as slurring of speech but in severe cases, complete loss of muscle tone can occur, resulting in the sufferer becoming limp and falling to the ground. Other features of the full narcolepsy/cataplexy syndrome include sleep paralysis, auditory and/or visual hallucinations and automatic behaviour.

SNORE Australia can diagnose narcolepsy with a full overnight diagnostic sleep study, followed next day by a specialised test called a Multiple Sleep Latency Test (MSLT).

Although narcolepsy cannot be cured, both the excessive sleepiness and cataplexy can usually be helped considerably with medications.

Diagnosing Narcolepsy

Narcolepsy can be diagnosed when there is a clinical history of sleepiness which cannot be explained by other causes of daytime tiredness (such as obstructive sleep apnoea or other sleep-disorders), and by a positive Multiple Sleep Latency Test (MSLT), which measures sleep latency and whether REM sleep occurs at sleep onset in multiple nap periods throughout the day (click here for more information on sleep studies and MSLT).

Treatments for Narcolepsy

Until the precise causes of narcolepsy are discovered, treatment for narcolepsy involves treating the symptoms, not the underlying cause. Treatment usually involves a combination of medication to counter daytime sleepiness and cataplexy, and lifestyle changes to accommodate the needs of narcoleptics.

Lifestyle Changes

In addition to medication to treat narcolepsy symptoms, there are a variety of lifestyle modifications that usually improve treatment efficacy and quality of life. These changes are individualised, and need to be discussed with your treating doctor, however may include:

  • Notify your family, friends and employer about your condition
  • Ensure a regular sleep schedule of bed times and rising times
  • Avoid periods of sleep-deprivation (such as staying 'out all night')
  • Schedule several short naps each day (10-15 minute naps, 2-3 times per day) to improve alertness and reduce the likelihood of sleep-attacks during activities
  • Have a short nap before driving or performing activities that require concentration; never drive when feeling sleepy or tired
  • Avoid occupations that involve excessive driving and operating heavy machinery
  • Avoid caffeine and nicotine
  • Avoid alcohol consumption
  • Keep physically active and eat a balanced diet
  • Join a patient support group.

Although narcolepsy is a lifelong condition, the symptoms can be managed by a combination of medications and lifestyle changes. People with the condition can live a long and productive life.

The common features of narcolepsy are excessive daytime tiredness, cataplexy, sleep-paralysis, hallucinations and automatic behaviour.

Marked Daytime Sleepiness

Marked, excessive daytime sleepiness is usually the first and most severe symptom that a person with narcolepsy will experience. This will often persist for many months or years before other symptoms such as cataplexy, sleep paralysis, hallucinations and automatic behaviour occur. Only 20-25% of narcoleptics will experience all of these symptoms. The order and severity of appearance of these 'peripheral' symptoms differ between individuals.

Sleep Paralysis

Sleep paralysis can occur in narcoleptic patients upon falling asleep or upon wakening. The sufferer finds that they are unable to move limbs, speak or breathe deeply, which can be frightening. The sleep-paralysis state is often accompanied by hallucinations. The person is fully aware of their surroundings and is able to recall the event later. Sleep paralysis rarely lasts longer than a few minutes, and always ends spontaneously. 3-5% of people without narcolepsy may experience sleep paralysis at some time.

Hallucinations

Hallucinations often accompany episodes of sleep paralysis. Hallucinations that occur at sleep onset are called hypnagogic hallucinations, and those that occur upon waking are called hypnopompic hallucinations. The hallucinations are often auditory or visual, comprised of simple noises, coloured shapes or parts of objects. Sometimes the experience can be cenesthopathic (feelings of light touch, rubbing) or a corporeal experience (such as a feeling of levitation).

Automatic Behaviour

Automatic behaviour occurs when routine, familiar or boring tasks (such as talking, cleaning or putting things away) are continued during sleep episodes. The individual often wakes with no memory of performing such activities. Automatic behaviour can be experienced by people without narcolepsy (such as when a person says they did something 'on auto-pilot'). However, automatic behaviour is reported in around 40% of narcoleptics.

Disturbed Sleep-Wake Cycles in Narcoleptics

When a person without narcolepsy is awake, the brain waves show a fast and regular rhythm (consisting predominantly of alpha waves). As the sufferer falls asleep, the brain waves become slow and more irregular (consisting of theta and delta waves), and the muscles which control the eyes are relaxed. These stages of sleep are called Non Rapid Eye Movement (NREM) sleep. After around 90 minutes of NREM sleep, the brain waves become more active and even though the eyelids remain closed, the eyes become active. This stage of sleep is called Rapid Eye Movement (REM) sleep, and this is the state of sleep where dreaming occurs.

In patients with narcolepsy, the cycle of wakefulness, NREM sleep and REM sleep is disturbed. REM sleep occurs soon after as the sufferer falls asleep, instead of following a period of NREM sleep. This is called sleep-onset REM ('SOREM'). REM sleep can also occur during the day (during "sleep attacks"). Also, physiological aspects of REM sleep (such as relaxation of muscle tone, which stops us from acting out our dreams during sleep) can occur inappropriately, resulting in episodes of cataplexy and sleep paralysis.

Normal patients go into dream sleep after about 90 minutes of non-dream sleep. Narcoleptics have abnormal sleep-wake cycles and can fall into dream sleep very rapidly (even when awake).

Narcolepsy Statistics

Approximately 3 million people world-wide have narcolepsy. The prevalence of narcolepsy is approximately 0.05% of the population, however it often goes unrecognised. Although narcolepsy is as common as many other conditions (such as Parkinson;s Disease or Multiple Sclerosis), fewer people know about narcolepsy, and it can sometimes be mistaken for other medical conditions such as depression, psychiatric illness, epilepsy, chronic fatigue syndrome, or a side-effect of medication.

Narcolepsy can occur in both men and women of any age; however symptoms typically do not start until after puberty. Consequently, the peak age of onset for narcolepsy is between 15 and 25 years. There is a smaller peak onset in women aged 35 to 45 years who are nearing menopause.

Even when narcolepsy symptoms present during adolescence, the educational, cognitive, occupational and psychological problems associated with narcolepsy and excessive daytime tiredness are usually not pronounced until late teenage years. However, narcolepsy can occur even in childhood.

The Cause of Narcolepsy

The precise cause of narcolepsy is currently unknown, but continuing research suggests a link between genetic conditions, auto-immune responses and environmental factors.

  • Most people with Narcolepsy carry human leukocyte antigen (HLA) DQB1*0602 - although this is also present in 12-38% of patients without narcolepsy.
  • Recent research has established that a protein produced in the brain (called hypocretin or orexin), which is responsible for controlling sleep patterns and appetite in humans, is absent or significantly reduced in people with narcolepsy. It is suggested that certain genetic variations may facilitate an auto-immune response, which leads to loss of the neurons in the brain, which produce this protein. Research in this area is continuing.