Narcolepsy

1. Big picture

Narcolepsy is a primary hypersomnia caused by abnormal regulation of the sleep-wake cycle. The patient cannot maintain stable wakefulness during the day and may show abnormal intrusion of rapid eye movement (REM) sleep phenomena into wakefulness.

The key exam sentence:

Narcolepsy causes excessive daytime sleepiness with recurrent irresistible sleep attacks, often with cataplexy, sleep paralysis, hypnagogic hallucinations, disturbed nocturnal sleep and automatic behavior.

The most important exam trap:

Cataplexy is not an epileptic seizure. It is sudden loss of muscle tone triggered by emotions, while consciousness is preserved.

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2. Definition

Narcolepsy is a chronic neurological sleep disorder characterized by:

• excessive daytime sleepiness;
• recurrent sleep attacks;
• REM sleep dysregulation;
• in many patients, cataplexy.

It is classified as a primary hypersomnia.

Primary hypersomnia means the main problem is excessive sleepiness due to intrinsic sleep-wake regulation dysfunction, not simply insufficient sleep, depression, medication, or sleep apnea.

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3. Classification