What is narcolepsy?
Narcolepsy is a chronic, neurological sleep disorder with no known cause. It involves the body's central nervous system. Narcolepsy is a genetic disorder, and is caused by a deficiency in the production of a neuropeptide (known as hypocretin or orexin) by a part of the brain called the hypothalamus.
The main characteristic of narcolepsy is excessive and overwhelming daytime sleepiness, even after adequate nighttime sleep. A person with narcolepsy is likely to become drowsy or to fall asleep at inappropriate times and places, and sleep attacks may occur with or without warning.
Attacks can occur repeatedly in a single day, drowsiness may persist for prolonged periods of time, and nighttime sleep may be fragmented with frequent awakenings.
What are the symptoms of narcolepsy?
The following are the most common symptoms of narcolepsy. However, individuals may experience symptoms differently. Symptoms may include:
Excessive daytime sleepiness (EDS). An overwhelming desire to sleep at inappropriate times.
Cataplexy. A sudden loss of muscle control ranging from slight weakness to total collapse.
Sleep paralysis. Being unable to talk or move for about 1 minute when falling asleep or waking up.
Hypnagogic and hypnopompic hallucinations. Vivid and often scary dreams and sounds reported when falling asleep (hypnagogic) or on awakening (hypnopompic).
Secondary or auxiliary symptoms include:
Automatic behavior. Performing routine tasks without conscious awareness of doing so, and often without memory of it.
Disrupted nighttime sleep, including multiple arousals
Dream-enacting behaviors, in which patients may act out their dreams
Other difficulties may result from one's continuing struggle to cope, including:
Feelings of intense fatigue and continual lack of energy
Difficulty in concentrating and memorizing
Vision (focusing) problems
Difficulties in handling alcohol
How is narcolepsy diagnosed?
A combination of EDS and cataplexy provide for a preliminary clinical diagnosis.
In addition to a complete medical history and physical examination, laboratory tests to confirm diagnosis and plan treatment may include:
Overnight polysomnogram (PSG). A sleep test to monitor various parameters during an entire night of sleep. This is to evaluate for other possible contributing sleep-related disorders.
Multiple Sleep Latency Test (MSLT). Measures sleep onset and how quickly rapid eye movement (REM) sleep occurs during 5 naps. A mean sleep latency on the 5 naps of 8 minutes or less, in conjunction with 2 or more sleep-onset REM periods, is considered diagnostic of narcolepsy.
Cerebral Spinal Fluid (CSF) hypocretin levels. A spinal tap for CSF to evaluate for possible hypocretin deficiency is used when there is concern about the possible diagnosis and other testing is either not possible or negative.
Genetic testing is no longer used because the human leukocyte antigen (HLA) markers may be negative in patients with narcolepsy and/or may be positive in patients who do not have narcolepsy. However, a link between reduced HLA markers and T cells, which are vital in the body's immune system, continued to be studied.
How is narcolepsy treated?
Specific treatment will be determined by your health care provider based on:
Your age, overall health, and medical history
Severity of the disease
Your tolerance for specific medications, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
The goal of treatment of narcolepsy is for the patient to remain as alert as possible during the day and to minimize any recurring episodes of cataplexy, while using a minimal amount of medication.
Medications. Excessive daytime sleepiness and cataplexy are treated separately, with central nervous system stimulants usually prescribed for EDS and antidepressants for cataplexy.
Nap therapy. Two or 3 short naps during the day may help control sleepiness and maintain alertness. Most patients with narcolepsy typically feel more alert and refreshed after awakening.