Narcolepsy is diagnosed through a number of tests including the Epworth Sleepiness Scale test, a polysomnogram and a multiple sleep latency test, according to WebMD. In the two weeks before any of these tests, most individuals must keep a sleep diary to track sleeping habits.
The Epworth Sleepiness Scale test involves the patient answering eight different questions using a scale from zero to three on how likely the person is to fall asleep, states WebMD. The total score ranges from zero to 24, and scores below 10 are considered normal. Any score over 10 is typically investigated.
A polysomnogram is performed in a sleep lab throughout the night, WebMD explains. This test transmits and records actions such as muscle movements, brain activity and breathing habits during sleep. The recordings are analyzed by a sleep specialist, and diagnosis of a sleep disorder may be the result. The morning after the polysomnogram, a test known as the multiple sleep latency test is performed. In this case, the individual is asked to take up to five naps in two-hour intervals. The test is designed to see how long it takes the patient to fall asleep, and those who fall asleep within five minutes are typically diagnosed with narcolepsy.