Narcolepsy Health Article

Definition

Narcolepsy is a sleep disorder that causes excessive sleepiness and frequent daytime sleep attacks.

Alternative Names

Daytime sleep disorder

Causes, incidence, and risk factors

Narcolepsy is a neurological disorder, not a mental illness. The exact cause is unknown. Genes may play a role, but it is not the only factor. Anxiety, however, does not cause narcolepsy.

The disorder may be made worse by conditions that cause insomnia such as disruption of work schedules.

Symptoms

Persons with narcolepsy have episodes of sudden daytime sleeping ("sleep attack"), usually preceded by drowsiness. It may be difficult for a young adult to stay awake during classes or work.

The sleep attacks:

• Last about 15 minutes each
• May occur several times during a day
• Usually happen after eating, but may occur at any time such as while driving, talking to someone, or during other situations where there is little movement

Sometimes, the person may have dreamlike hallucinations before sleep or during the sleep episode. The person wakes up feeling refreshed after each brief sleep episode.

Narcolepsy may also be associated temporary and sudden muscle weakness called cataplexy, that is usually brought on by strong emotions. This may involve:

• Sudden loss of muscle tone
  • May be associated with emotional reactions such as laughter or anger
  • May be similar to seizures
• Temporary inability to use muscles (sleep paralysis)
  • Occurs immediately upon awakening
  • Occurs at the onset of drowsiness

Signs and tests

The doctor will perform a physical exam and order blood work to rule out conditions that can cause similar symptoms. Conditions that can cause excessive sleepiness include:

• Insomnia and other sleep disorders
• Restless leg syndrome
• Seizures
• Sleep apnea
• Other medical, psychiatric, or neurological diseases

Other tests may include:

• ECG (measures the heart's electrical activity)
• EEG (brain activity measurements)
• Monitoring of breathing
• Genetic testing to look for narcolepsy gene

Tests will also include a sleep study (polysomnogram). The Multiple Sleep Latency Test (MSLT) may be used to help diagnose narcolepsy. This test measures how long it takes you to fall asleep during a daytime nap. Patients with narcolepsy fall asleep much faster.