Narcolepsy is considered a primary hypersomnia (excessive sleepiness) condition. Primary means the condition is not caused by another disease. 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)
- Dreamlike states between waking and sleeping (called hypnagogic or hypnopompic hallucinations)
Rapid eye movement (REM) 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. It is sometime described as an irresistible daytime need for naps, which will generally refresh the patient. These events may be characterized by the following behaviors:
- Patients often have periods of drowsiness every 3 or 4 hours that 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.
Review Date: 07/04/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.