Risk Factors
Narcolepsy affects around 1 in 2,000 people. Experts estimate that around 135,000 – 200,000 Americans have narcolepsy, but the number may be higher. Only about 25% of people who have narcolepsy are actually diagnosed with the disorder. Patients are often mistakenly diagnosed with other causes such as psychiatric or emotional problems. Many patients wait decades before they are properly diagnosed.
Ethnic Differences
Genetic factors may influence narcolepsy's prevalence in different populations. For example, studies have found much higher rates among Japanese and much lower rates among people in Israel. A 2002 study suggested, however, that the disease is very consistent among all ethnic groups and does not vary in severity or symptoms.
Age
Narcolepsy symptoms usually first appear in adolescence or young adulthood. However, narcolepsy can begin at any age. Growing evidence suggests that the disorder may emerge in early childhood in many patients. People who develop it at a young age often have a family history of the disease and a severe condition, suggesting that genetic factors are important in this group. A 2006 study found that children with frequent headaches are more likely to develop narcolepsy and excessive daytime sleepiness than other children. The researchers recommended that pediatricians ask about narcolepsy symptoms when treating children with chronic headaches.
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