Narcolepsy is a chronic neurological disorder characterized by recurrent periods of an irresistible urge to sleep accompanied by three accessory events:

1. 1. 

   Cataplexy—attacks of loss of muscle tone, sometimes with actual collapse, during which the individual always remains conscious.

2. 2. 

   Hypnagogic hallucinations—hallucinations which occur between sleep and wakening.

3. 3. 

   Sleep paralysis—a transient sensation of being unable to move while drifting into sleep or upon awakening. In addition, some persons have periods of automatic behavior and most have disturbed nocturnal sleep.

There are no physical abnormalities in narcolepsy, and with the exception of sleep studies, laboratory studies will be normal. The sleep symptoms will range from mild drowsiness to severe sleepiness in which the individuals spend the entire day drifting in and out of sleep, unable to work, play or supervise the home. Sleep periods range from a few seconds to 30 minutes. The sensation is described as ordinary but uncontrollable drowsiness. When observed by others, the sleep appears natural and is readily interrupted by stimuli. Once awakened, the narcoleptic patient is alert. Not all individuals will have all of the symptoms. Cataplexy, however, is observed in 70 percent of all cases, and its associated presence is ordinarily sufficient to establish narcolepsy, without laboratory sleep studies.

Although narcolepsy and epilepsy are not truly comparable illnesses, when evaluating medical severity, the closest listing to equate narcolepsy with is Listing 11.02, Epilepsy.

The severity of narcolepsy should be evaluated after a period of 3 months of prescribed treatment. It is not necessary to obtain an electroencephalogram (EEG) in narcolepsy cases. A routine EEG is usually normal, and when special attempts are made to obtain abnormal rapid eye movement (REM) sleep patterns, they may or may not be present even in true cases of narcolepsy. Also, narcolepsy is not usually treated with anticonvulsant medication, but is most frequently treated by the use of drugs such as stimulants and mood elevators for which there are no universal laboratory blood level determinations available. Finally, it is important to obtain from an ongoing treatment source a description of the medications used and the response to the medication, as well as an adequate description of the claimant's alleged narcoleptic attacks and any other secondary events such as cataplexy, hypnagogic hallucinations or sleep paralysis.