Narcolepsy

What Is Narcolepsy?

Narcolepsy is a rare neurological disorder that is characterized by excessive daytime sleepiness and uncontrollable episodes of sleep. It is usually associated with other symptoms such as: sleep paralysis, cataplexy, and hallucinations.

The sudden episodes of sleep (sleep attacks) associated with narcolepsy can last anywhere from a few seconds all the way up to 30 minutes. It is not uncommon for these attacks to occur several times a day, regardless of how much sleep the individual got the night before.

Narcolepsy is often left undiagnosed for many years before treatment is sought out.

Sadly, if you suffer from narcolepsy then you will likely have the condition for life. There is no cure that exists for insomnia at this point in time.

Symptoms

Symptoms of narcolepsy will usually appear between the ages of 15 and 30. The most common symptoms are:

As the name suggests, excessive daytime sleepiness is characterised by a feeling of sleepiness that is persistant throughout the day.

Sleep paralysis occurs when the body wakes up during REM sleep. During this time the body is unable to move, but the individual will be aware of their surroundings. This occurrence can be quite scary as sleep paralysis is often associated with hallucinations. Figures have shown that roughly 2 in 5 people have experienced sleep paralysis at some point in their lifetime.

Cataplexy is defined by a sudden loss of muscle tone that is usually triggered by an extreme emotion such as laughter, or excitement.

Hypnogogic hallucinations occur during the transition between wakefulness and sleep. These hallucinations can seem very realist, although they are only imaginary. The opposite is known as hypnopompic hallucinations, which occur during the transition between sleep and wakefulness.

Patients with narcolepsy may find that they fall asleep during the day with little to no warning. When this happens the patient rapidly transitions into rapid eye movement (REM) sleep – which is the stage of sleep where dreaming is said to occur. During this stage the individual will experience a temporary loss of muscle tone, and rapid movements of the eyes.

Narcolepsy can develop over a long period of time, or can appear abruptly. Normal everyday activities can become increasingly difficult if you suffer from insomnia due to fatigue, and a decrease in cognitive function associated with the disorder.

Depression is also a common symptom that is related to narcolepsy.

There are many reasons why you could be feeling tired, so it is important that you rule out all of the other possible options. You may have idiopathic insomnia if you are not confirmed to have narcolepsy.

What Is Idiopathic Insomnia?

Patients who suffer from idiopathic insomnia do not enter into REM sleep immediately after falling asleep.

Causes

Narcolepsy is caused by the impairment of the part of the brain that controls the regulation of sleep.

It is widely believed that narcolepsy is associated with a deficiency of the neuropeptide orexin (also known as hypocretin), which is involved in the regulation of sleep and our arousal states.

Narcolepsy can also be inherited if you have a family member who also has the condition.

Treatment

Unfortunately there is no cure for narcolepsy, and there is also no feasible way to prevent it. In saying that though, the symptoms associated with narcolepsy can be treated with certain medications. This includes:

  • Stimulants (i.e. modafinil)
  • Antidepressants

Medication will not be able to alleviate the symptoms of narcolepsy completely, but they should be able to help reduce them.

If you suffer from narcolepsy then you should look to avoid doing things that might put you in danger, such as driving, or operating heavy machinery.

You may find it beneficial to take frequent naps throughout the day to feel more energized.

Modafinil

Modafinil is often prescribed to patients who suffer from narcolepsy. The drug has been found to be pretty well-tolerated, and is useful in controlling the sleepiness associated with narcolepsy. In addition, it makes you feel more energized.

Diagnosis

If you believe you have narcolepsy then it would be a good idea to get yourself checked out by a health professional. They will be able to assess your condition and either refer you to a sleep specialist, or let you know what your treatment options are.

Multiple Sleep Latency Test

You may need to undergo a test known as a Multiple Sleep Latency Test (MSLT), which is a standard tool used for to diagnose narcolepsy. The MSLT is used to measure the amount of time it takes for you to fall asleep in a quiet setting during the daytime. The test is generally performed in a sleep laboratory.

The MSLT consists of five scheduled nap periods where you will be expected to try and sleep during these times. This will take place in a dark, quiet, and comfortable setting for you to try and sleep easier. Measurements are taken during this time to see how long it takes you to fall asleep, and to see whether or not you rapidly enter into REM sleep after falling asleep.

During these time periods you will be connected to several sensors, which are used to determine what stage of sleep you are in. After 15 minutes of sleep you will be woken up, and then expected to wait 2 hours for the next scheduled nap time to begin. If you were unable to sleep after 20 minutes then the nap time will halt.

Types of Narcolepsy

According to the International Classification of Sleep Disorders (ICSD-3) there are two types of narcolepsy: type 1, and type 2. [1]

The diagnostic criteria for type 1 narcolepsy can be seen below. Please not that both A and B must be met.

  1. The patient has daily periods of irrepressible need to sleep or daytime lapses into sleep occurring for at least 3 months
  2. The presence of one or both of the following:
  3. Cataplexy (as defined under ‘Essential features’) and a mean sleep latency of <8 min and two or more sleep-onset REM periods (SOREMPs) on an MSLT performed according to standard techniques. A SOREMP (within 15 min of sleep onset) on the preceding nocturnal polysomnogram may replace one of the SOREMPs on the MSLT
  4. CSF hypocretin-1 concentration, measured by immunoreactivity, is either ≤ 110 pg mL-1 or <1/3 of mean values obtained in normal subjects with the same standardized assay.

The diagnostic criteria for type 2 narcolepsy can be seen below. Please not that ALL criteria A to E must be met.

  1. The patient has daily periods of irrepressible need to sleep or daytime lapses in sleep occurring for at least 3 months
  2. A mean sleep latency of ≤8 min and two or more sleep-onset REM periods (SOREMPs) are found on a MSLT performed according to standard techniques. A SOREMP (within 15 min of sleep onset) on the preceding nocturnal polysomnogram may replace one of the SOREMPs on the MSLT
  3. Cataplexy is absent
  4. Either CSF hypocretin-1 concentration has not been measured or CSF hypocretin-1 concentration measured by immunoreactivity is either >110 pg mL-1 or >1/3 of mean values obtained in normal subjects with the same standardized assay
  5. The hypersomnolence and/or MSLT findings are not explained more clearly by other causes such as insufficient sleep, obstructive sleep apnoea, delayed sleep phase disorder or the effect of medication or substances or their withdrawal.

Prevalence

Narcolepsy is estimated to affect around 1 in 2000 people.

References

  1. Bassetti, C, Dogas, Z, Peigneux, P., 2014. Sleep Medicine Textbook. 1st ed. Regensburg: European Sleep Research Society (ESRS).

DISCLAMER: The information on this page is intended for educational purposes only. It should not be used as a substitute for proper medical attention. If you would like to know more then please read our disclaimer.

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