Narcolepsy
How is the condition diagnosed?
Diagnosis of narcolepsy starts with a full family medical history. This is important because narcolepsy is often genetic. A physical examination is done to rule out any other causes of the symptoms. Finally, diagnosis is made after a visit to a sleep laboratory.
At the sleep laboratory:
Brain waves, body movements, and nerve and muscle function are observed, measured, and studied while the person is sleeping at night.
A sleep study, known as a polysomnogram, or PSG, is done to determine the degree of the person's excessive daytime sleepiness.
A multiple sleep latency test is usually performed. This test measures the time it takes for the person to fall asleep and go into deep sleep. The test is often done during naps and nighttime sleep. Most people progress into REM or rapid eye movement sleep in about 1-1/2 hours. A person with narcolepsy will fall into REM sleep right away.
If the diagnosis is uncertain, there is a genetic blood test that measures antigens found in people who often have narcolepsy. A positive result would support, but not prove, a diagnosis of narcolepsy.
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