Narcolepsy Symptoms and Causes
Narcolepsy is a chronic, neurological sleep disorder with no known cause. It involves the body's central nervous system. Narcolepsy is a genetic disorder, but what causes narcolepsy is not yet known.
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.
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 one minute when falling asleep or waking up.
- Hypnagogic hallucinations — vivid and often scary dreams and sounds reported when falling asleep.
- Automatic behavior — performing routine tasks without conscious awareness of doing so, and often without memory of it.
- disrupted nighttime sleep, including multiple arousals
- Feelings of intense fatigue and continual lack of energy
- Difficulty in concentrating and memorizing
- Vision (focusing) problems
- Eating binges
- Weak limbs
- Difficulties in handling alcohol
Most people who have narcolepsy have low levels of hypocretin. This is a chemical in the brain that helps promote wakefulness. What causes low hypocretin levels isn't well understood. Researchers think that certain factors may work together to cause a lack of hypocretin. These factors may include:
- Heredity. Some people may inherit a gene that affects hypocretin. Up to 10 percent of people who have narcolepsy report having a relative who has the same symptoms.
- Brain injuries caused by conditions such as brain tumors, strokes, or trauma (for example, car accidents or military-related wounds).
- Autoimmune disorders. With these disorders, the body's immune system mistakenly attacks the body's cells and tissues. An example of an autoimmune disorder is rheumatoid arthritis.
- Low levels of histamine, a substance in the blood that promotes wakefulness.
Some research suggests that environmental toxins may play a role in triggering narcolepsy. Toxins may include heavy metals, pesticides and weed killers, and secondhand smoke.
Heredity alone doesn't cause narcolepsy. You also must have at least one other factor, such as one of those listed above, to develop narcolepsy.