Introduction

Introduction

The word narcolepsy comes from two Greek words roughly translated as "seized by numbness". The two primary symptoms in narcolepsy reflect this phrase:

• Excessive daytime sleepiness, with frequent daily sleep attacks or a need to take several naps during the day.
• Temporary and sudden muscle weakness (called cataplexy), usually brought on by strong emotions.

Some, but not all patients experience other symptoms:

• Microsleep episodes, in which the patient behaves automatically but without conscious awareness.
• A sense of paralysis that occurs between wakefulness and sleep (called atonia).
• Dream-like states between waking and sleeping (called hypnagogic hallucinations).
• Periodic leg movements during sleep (periodic limb movement disorder).

REM (rapid eye movement) sleep is abnormal in narcolepsy. In fact, narcolepsy is sometimes defined as the loss of boundaries between wakefulness, non-REM sleep, and REM sleep. REM sleep is the active, dreaming phase of sleep.

Primary Symptoms of Narcolepsy

Excessive Sleepiness. All people with narcolepsy experience excessive sleepiness during the day with episodes of falling asleep rapidly and inappropriately, even when fully involved in an activity. These events may be characterized by the following behaviors:

• Periods of drowsiness may occur every 3 or 4 hours and usually end in short naps.
• Patients may sleep for a few minutes, particularly if they are in an awkward position or for a few hours if they are lying down.
• Patients often underestimate the duration of their drowsy periods and may not recall clearly their behavior during that time.

Cataplexy. Cataplexy is an abrupt loss of muscle tone or strength that results in an inability to move and always occurs during wakefulness. It occurs in about two-thirds of narcolepsy patients and may be triggered by the following events:

• Sudden emotion, usually anger or laughter (the most common trigger)
• Following a heavy meal
• During periods of stress

Muscle reflexes are completely absent during a cataplectic attack. Cataplectic attacks can be very minimal and appear as passing weakness or affecting only the eyelids and face. They may, on the other hand, be so severe that they weaken the whole body. The most severe form is called status cataplectics, which occurs repeatedly for hours or days. Abrupt withdrawal from certain drugs used to treat narcolepsy, notably clomipramine, can cause status cataplectics.