Narcolepsy and Idiopathic Hypersomnia

What is narcolepsy?

Narcolepsy is a neurological disorder where the most prominent problem is daytime sleepiness. There are two fundamental problems at work in narcolepsy: the impairment of the ability to stay awake, and a tendency to proceed too quickly into dream (REM) sleep.

What are the symptoms of narcolepsy?

Excessive daytime sleepiness is almost always the first symptom to appear, and it may be present for several years before any other symptoms occur.  Other symptoms include brief episodes of muscle weakness (“cataplexy”), awakening with a brief feeling of the inability to move (“sleep paralysis”), and hallucinatory symptoms (sound, sight, or skin sensations) that occur during drowsiness. It usually becomes symptomatic in early adulthood, but a person may be able to adjust to the symptoms for a period of time, delaying diagnosis.  The symptoms can range in intensity from mild sleepiness that requires no medical therapy, to sudden bouts of sleep attack causing physical collapse.

Who is at risk for narcolepsy?

It is estimated to occur in one out of 1,500 otherwise normal people, but it is seen somewhat more often in people with neurological disorders or head trauma.  

What is idiopathic hypersomnia?

Idiopathic hypersomnia is less common, and is also seen with greater frequency in neurological conditions.  Daytime sleepiness is the only symptom in idiopathic hypersomnia, occurring despite large amounts of sleep at night.  There is no disturbance of dream (REM) sleep in idiopathic hypersomnia, simply a constant sleepiness that impairs daytime function.

How are narcolepsy and idiopathic hypersomnia diagnosed?

In either of these conditions, the diagnosis can only be made by a combination of sleep studies, including a nocturnal Polysomnogram (PSG) to rule out other sleep disorders, and a Multiple Sleep Latency Test (MSLT) that involves multiple naps the next day.

How are narcolepsy and idiopathic hypersomnia treated?

Treatment of these conditions may include a combination of change in daytime habits and the use of daytime stimulant medication. For narcolepsy, other medications may be used to prevent the attacks of muscle weakness. It is expected that treatment will need to be adjusted over time.